Molecular immunobiology of macrophages: recent progress

The progress in titanium alloys used as biomedical implants: From the view of reactive oxygen species

Titanium and Titanium alloys are widely used as biomedical implants in oral and maxillofacial surgery, due to superior mechanical properties and biocompatibility. In specific clinical populations such as the elderly, diabetics and patients with metabolic diseases, the failure rate of medical metal implants is increased significantly, putting them at increased risk of revision surgery. Many studies show that the content of reactive oxygen species (ROS) in the microenvironment of bone tissue surrounding implant materials is increased in patients undergoing revision surgery. In addition, the size and shape of materials, the morphology, wettability, mechanical properties, and other properties play significant roles in the production of ROS. The accumulated ROS break the original balance of oxidation and anti-oxidation, resulting in host oxidative stress. It may accelerate implant degradation mainly by activating inflammatory cells. Peri-implantitis usually leads to a loss of bone mass around the implant, which tends to affect the long-term stability and longevity of implant. Therefore, a great deal of research is urgently needed to focus on developing antibacterial technologies. The addition of active elements to biomedical titanium and titanium alloys greatly reduce the risk of postoperative infection in patients. Besides, innovative technologies are developing new biomaterials surfaces conferring anti-infective properties that rely on the production of ROS. It can be considered that ROS may act as a messenger substance for the communication between the host and the implanted material, which run through the entire wound repair process and play a role that cannot be ignored. It is necessary to understand the interaction between oxidative stress and materials, the effects of oxidative stress products on osseointegration and implant life as well as ROS-induced bactericidal activity. This helps to facilitate the development of a new generation of well-biocompatible implant materials with ROS responsiveness, and ultimately prolong the lifespan of implants.

FoxJ1 inhibits African swine fever virus replication and viral S273R protein decreases the expression of FoxJ1 to impair its antiviral effect

African swine fever (ASF) is a highly pathogenic swine infectious disease that affects domestic pigs and wild boar, which is caused by the African swine fever virus (ASFV). ASF has caused huge economic losses to the pig industry and seriously threatens global food security and livestock health. To date, there is no safe and effective commercial vaccine against ASF. Unveiling the underlying mechanisms of ASFV-host interplay is critical for developing effective vaccines and drugs against ASFV. In the present study, RNA-sequencing, RT-qPCR and Western blotting analysis revealed that the transcriptional and protein levels of the host factor FoxJ1 were significantly down-regulated in primary porcine alveolar macrophages (PAMs) infected by ASFV. RT-qPCR analysis showed that overexpression of FoxJ1 upregulated the transcription of type I interferon and interferon stimulating genes (ISGs) induced by poly(dA:dT). FoxJ1 revealed a function to positively regulate innate immune response, therefore, suppressing the replication of ASFV. In addition, Western blotting analysis indicated that FoxJ1 degraded ASFV MGF505-2R and E165R proteins through autophagy pathway. Meanwhile, RT-qPCR and Western blotting analysis showed that ASFV S273R inhibited the expression of FoxJ1. Altogether, we determined that FoxJ1 plays an antiviral role against ASFV replication, and ASFV protein impairs FoxJ1-mediated antiviral effect by degradation of FoxJ1. Our findings provide new insights into the antiviral function of FoxJ1, which might help design antiviral drugs or vaccines against ASFV infection.

•

FoxJ1 inhibits ASFV replication by degrading ASFV MGF505-2R and E165R proteins via autophagy.

•

FoxJ1 enhances type I IFN response, showing an essential antiviral role.

•

ASFV S273R protein inhibits FoxJ1 expression to impair its antiviral effect.

Inflammatory Effects of Bothrops Phospholipases A2: Mechanisms Involved in Biosynthesis of Lipid Mediators and Lipid Accumulation

Phospholipases A₂s (PLA₂s) constitute one of the major protein groups present in the venoms of viperid and crotalid snakes. Snake venom PLA₂s (svPLA₂s) exhibit a remarkable functional diversity, as they have been described to induce a myriad of toxic effects. Local inflammation is an important characteristic of snakebite envenomation inflicted by viperid and crotalid species and diverse svPLA₂s have been studied for their proinflammatory properties. Moreover, based on their molecular, structural, and functional properties, the viperid svPLA₂s are classified into the group IIA secreted PLA₂s, which encompasses mammalian inflammatory sPLA₂s. Thus, research on svPLA₂s has attained paramount importance for better understanding the role of this class of enzymes in snake envenomation and the participation of GIIA sPLA₂s in pathophysiological conditions and for the development of new therapeutic agents. In this review, we highlight studies that have identified the inflammatory activities of svPLA₂s, in particular, those from Bothrops genus snakes, which are major medically important snakes in Latin America, and we describe recent advances in our collective understanding of the mechanisms underlying their inflammatory effects. We also discuss studies that dissect the action of these venom enzymes in inflammatory cells focusing on molecular mechanisms and signaling pathways involved in the biosynthesis of lipid mediators and lipid accumulation in immunocompetent cells.

Novel mucosal adjuvant, mastoparan-7, improves cocaine vaccine efficacy

Cocaine is one of the most potent and addictive psychostimulants known and there are no available pharmacotherapies to treat cocaine addiction. Here we describe a novel cocaine vaccine employing the mucosal adjuvant and mast cell-activating oligopeptide, mastoparan-7 (M7), to achieve optimal IgA antibody responses in mucosal secretions and effective induction of humoral immunity using a short immunization protocol. This formulation, using a hapten-carrier system to deliver cocaine as antigen, also reduced cocaine penetration of the blood brain barrier and protected mice from its psychoactive effects by reducing cocaine-induced locomotion. Surprisingly, the magnitude of cocaine-specific antibody titers induced by each adjuvant was not the major determinant of functional protection from cocaine challenge. A side-by-side comparison of the two haptens, cocaine and its analog GNC demonstrated that cocaine haptenation resulted in superior functional protection when used in combination with the novel mucosal adjuvant, M7. These results provide a new potential strategy for combatting cocaine addiction through mucosal vaccination.

Carbohydrate-based nanocarriers and their application to target macrophages and deliver antimicrobial agents

Many deadly infections are produced by microorganisms capable of sustained survival in macrophages. This reduces exposure to chemadrotherapy, prevents immune detection, and is akin to criminals hiding in police stations. Therefore, the use of glyco-nanoparticles (GNPs) as carriers of therapeutic agents is a burgeoning field. Such an approach can enhance the penetration of drugs into macrophages with specific carbohydrate targeting molecules on the nanocarrier to interact with macrophage lectins. Carbohydrates are natural biological molecules and the key constituents in a large variety of biological events such as cellular communication, infection, inflammation, enzyme trafficking, cellular migration, cancer metastasis and immune functions. The prominent characteristics of carbohydrates including biodegradability, biocompatibility, hydrophilicity and the highly specific interaction of targeting cell-surface receptors support their potential application to drug delivery systems (DDS). This review presents the 21^st century development of carbohydrate-based nanocarriers for drug targeting of therapeutic agents for diseases localized in macrophages. The significance of natural carbohydrate-derived nanoparticles (GNPs) as anti-microbial drug carriers is highlighted in several areas of treatment including tuberculosis, salmonellosis, leishmaniasis, candidiasis, and HIV/AIDS.

Development of vaccines against African swine fever virus

An outbreak in the Caucasus in 2007 initiated the spread of ASFV through Russia and Eastern Europe, subsequently affecting Ukraine, Belarus, Poland, the Baltic States, the Czech Republic, Moldova, Romania and Bulgaria. The declaration of outbreaks in China and Central Europe in August 2018, definitely confirms the serious threat that the extension of ASF represents for the global swine industry and the environment. Despite the efforts of several groups to generate a vaccine against ASFV, currently only control and eradication measures are available based mainly on the early detection and implementation of strict sanitary procedures, including the mass slaughter of animals, both domestic and wild boar. However, the rapid spread of the disease shows that these actions are clearly insufficient to control the current pandemic situation, and the development of a vaccine is urgently required.

Analysis of peptide-SLA binding by establishing immortalized porcine alveolar macrophage cells with different SLA class II haplotypes

Primary porcine alveolar macrophages (PAM) are useful for studying viral infections and immune response in pigs; however, long-term use of these cells is limited by the cells’ short lifespan. We immortalized primary PAMs by transfecting them with both hTERT and SV40LT and established two immortalized cell lines (iPAMs) actively proliferating even after 35 passages. These cells possessed the characteristics of primary PAMs, including strong expression of swine leukocyte antigen (SLA) class II genes and the inability to grow anchorage-independently. We characterized their SLA genes and subsequently performed peptide-SLA binding assays using a peptide from porcine circovirus type 2 open reading frame 2 to experimentally measure the binding affinity of the peptide to SLA class II. The number of peptides bound to cells measured by fluorescence was very low for PK15 cells (7.0% ± 1.5), which are not antigen-presenting cells, unlike iPAM61 (33.7% ± 3.4; SLA-DQA*0201/0303, DQB1*0201/0901, DRB1*0201/1301) and iPAM303 (73.3% ± 5.4; SLA DQA*0106/0201, DQB1*0202/0701, DRB1*0402/0602). The difference in peptide binding between the two iPAMs was likely due to the allelic differences between the SLA class II molecules that were expressed. The development of an immortal PAM cell panel harboring diverse SLA haplotypes and the use of an established method in this study can become a valuable tool for evaluating the interaction between antigenic peptides and SLA molecules and is important for many applications in veterinary medicine including vaccine development.

Variations of Cytokine Levels and Production in CAPD Patients

Macrophages, predominant cells in dialysates of patients on CAPD without peritonitis, produce a wide variety of substances including cytokines. The aim of this study was to examine the cytokine production in five uninfected patients. This work investigated the presence in dialysates of interleukin-1ß, interleukin-6, interleukin-8, tumor necrosis factor α and the ability of peritoneal macrophages to produce these cytokines. These results were compared with values obtained from control group in non-uremic conditions (peritoneal lavage with isotonic saline or dialysis fluid). All cytokines were detectable in dialysates. Interindividual variations in cytokine concentration in dialysates were wider than variations of production of cytokines ex vivo by stimulated and unstimulated cells. In control group, dialysis fluid inhibited the cytokine production and with isotonic saline, cells produced less cytokines than dialysis patients'cells. The highest levels of interleukin-1 and tumor necrosis factor in dialysates and the highest capacity to respond to LPS were observed in patients having the shortest duration of dialysis. The variability observed did not seem to be due to cells themselves but to their environment.

African Swine Fever Virus Biology and Vaccine Approaches

African swine fever (ASF) is an acute and often fatal disease affecting domestic pigs and wild boar, with severe economic consequences for affected countries. ASF is endemic in sub-Saharan Africa and the island of Sardinia, Italy. Since 2007, the virus emerged in the republic of Georgia, and since then spread throughout the Caucasus region and Russia. Outbreaks have also been reported in Belarus, Ukraine, Lithuania, Latvia, Estonia, Romania, Moldova, Czech Republic, and Poland, threatening neighboring West European countries. The causative agent, the African swine fever virus (ASFV), is a large, enveloped, double-stranded DNA virus that enters the cell by macropinocytosis and a clathrin-dependent mechanism. African Swine Fever Virus is able to interfere with various cellular signaling pathways resulting in immunomodulation, thus making the development of an efficacious vaccine very challenging. Inactivated preparations of African Swine Fever Virus do not confer protection, and the role of antibodies in protection remains unclear. The use of live-attenuated vaccines, although rendering suitable levels of protection, presents difficulties due to safety and side effects in the vaccinated animals. Several African Swine Fever Virus proteins have been reported to induce neutralizing antibodies in immunized pigs, and vaccination strategies based on DNA vaccines and recombinant proteins have also been explored, however, without being very successful. The complexity of the virus particle and the ability of the virus to modulate host immune responses are most likely the reason for this failure. Furthermore, no permanent cell lines able to sustain productive virus infection by both virulent and naturally attenuated African Swine Fever Virus strains exist so far, thus impairing basic research and the commercial production of attenuated vaccine candidates.

Approaches and Perspectives for Development of African Swine Fever Virus Vaccines

African swine fever (ASF) is a complex disease of swine, caused by a large DNA virus belonging to the family Asfarviridae. The disease shows variable clinical signs, with high case fatality rates, up to 100%, in the acute forms. ASF is currently present in Africa and Europe where it circulates in different scenarios causing a high socio-economic impact. In most affected regions, control has not been effective in part due to lack of a vaccine. The availability of an effective and safe ASFV vaccines would support and enforce control-eradication strategies. Therefore, work leading to the rational development of protective ASF vaccines is a high priority. Several factors have hindered vaccine development, including the complexity of the ASF virus particle and the large number of proteins encoded by its genome. Many of these virus proteins inhibit the host's immune system thus facilitating virus replication and persistence. We review previous work aimed at understanding ASFV-host interactions, including mechanisms of protective immunity, and approaches for vaccine development. These include live attenuated vaccines, and "subunit" vaccines, based on DNA, proteins, or virus vectors. In the shorter to medium term, live attenuated vaccines are the most promising and best positioned candidates. Gaps and future research directions are evaluated.

Phenotyping and susceptibility of established porcine cells lines to African Swine Fever Virus infection and viral production

African swine fever virus (ASFV) is a highly pathogenic, double-stranded DNA virus with a marked tropism for cells of the monocyte-macrophage lineage, affecting swine species and provoking severe economic losses and health threats. In the present study, four established porcine cell lines, IPAM-WT, IPAM-CD163, C∆2+ and WSL, were compared to porcine alveolar macrophage (PAM) in terms of surface marker phenotype, susceptibility to ASFV infection and virus production. The virulent ASFV Armenia/07, E70 or the naturally attenuated NHV/P68 strains were used as viral models. Cells expressed only low levels of specific receptors linked to the monocyte/macrophage lineage, with low levels of infection overall, with the exception of WSL, which showed more efficient production of strain NHV/P68 but not of strains E70 and Armenia/07.

Modulation of recombinant antigenic constructs containing multi-epitopes towards effective reduction of atherosclerotic lesion in B6;129S-Ldlr(tm1Her)Apob(tm2Sgy)/J mice

Atherosclerosis is increasingly recognized as a complex chronic inflammatory disease. Many more studies have extended vaccination against atherosclerosis by using epitopes from self-antigens or beyond and demonstrated that vaccination with antigens or derivatives could reduce the extent of the lesions in atherosclerosis-prone mice. Our previous study has demonstrated that construct AHHC [ApoB100688-707 + hHSP60303-312 + hHSP60153-163 + Cpn derived peptide (C)] significantly reduced atherosclerotic lesion. The aim of this study was to investigate whether AHHC can be modulated towards increased lesion reduction in mice by creating two other derivatives with a sequential epitope-substitution named RHHC in which A was replaced by an "R" (C5aR1-31) and RPHC with a further "H" (hHSP60303-312) conversion into "P" (protease-activated receptor-142-55) in mice. Antigenic epitopes were incorporated into a dendroaspin scaffold. Immunization of B6;129S-Ldlrtm1HerApobtm2Sgy/J mice with three constructs elicited production of high levels of antibodies against each epitope (apart from hHSP60153-163 and P which induced a low antibody response). Histological analyses demonstrated that the mice immunized with either RPHC or RHHC showed significant reductions in the size of atherosclerostic lesions compared to those with AHHC (69.5±1.1% versus 55.7±3.4%, P<0.01 or 65.6±1.3% versus 55.7±3.4%, P<0.01). Reduction of plaque size in the aortic sinus and descending aorta correlated with alterations in cellular immune responses when compared with controls. We conclude that a recombinant construct RPHC may provide new antigenic and structural features which are favorable for significant reduction in atherosclerotic lesion formation. This approach offers a novel strategy for developing anti-atherosclerotic agents.

Immunization With a Combination of 2 Peptides Derived From the C5a Receptor Significantly Reduces Early Atherosclerotic Lesion in Ldlr tm1Her Apob tm2Sgy J Mice

Objective—

The goal of this study was to assess whether immunization of Ldlr tm1Her Apob tm2Sgy J mice with 2 peptides located at the N-terminus of the C5a receptor (C5aR), either alone or in combination, is effective in reducing atherosclerotic lesions.

Methods and Results—

Five- to 6-week-old female Ldlr tm1Her Apob tm2Sgy J mice were immunized using a repetitive immunization multiple sites strategy with keyhole limpet hemocyanin-conjugated peptides derived from the C5aR, either alone (designated as C5aR-P1 [aa 1–21] and C5aR-P2 [aa 19–31]) or in combination (designated as C5aR-P1+C5aR-P2). Mice were fed a high-fat diet for 10 weeks. Lesions were evaluated histologically; local and systemic immune responses were analyzed by immunohistochemistry of aorta samples and cytokine measurements in plasma samples and splenocyte supernatants. Immunization of Ldlr tm1Her Apob tm2Sgy J mice with these peptides elicited high concentrations of antibodies against each peptide. Immunization with the single peptide inhibited plaque development. Combined inoculation with C5aR-P1+C5aR-P2 had an additive effect on reducing the lesion in the aorta sinus and descending aortas when compared with controls. This effect correlated with cellular infiltration and cytokine/chemokine secretion in the serum or in stimulated spleen cells as well as specific cellular immune responses when compared with controls.

Conclusion—

Immunization of mice with C5aR-P1 and C5aR-P2, either alone or in combination, was effective in reducing early atherosclerotic lesion development. The combined peptide is more potential than either epitope alone to reduce atherosclerotic lesion formation through the induction of a specific Treg cell response as well as blockage of monocyte differentiation into macrophages.

Atomic force microscopy-based molecular studies on the recognition of immunogenic chlorinated ovalbumin by macrophage receptors

This report presents simple and reliable approach developed to study the specific recognition events between chlorinated ovalbumin (OVA) and macrophages using atomic force microscopy (AFM). Thanks to the elimination of nonspecific adhesion, the interactions of the native and chlorinated OVA with a membrane of macrophages could be quantified using exclusively the so-called adhesion frequency (AF). The proposed system not only enabled the application of AFM-based force measurements for such poorly defined ligand-receptor pairs but also significantly improved both the acquisition and the processing of the data. The proteins were immobilized on the gold-coated AFM tips from the aqueous solutions containing charged thiol adsorbates. Such surface dilution of the proteins ensured the presence of single or just a few macromolecules at the tip-surface contact. The formation of negatively charged monolayer on the tip dramatically limited its nonspecific interactions with the macrophage surface. In such systems, AF was used as a measure of the recognition events even if the interaction forces varied significantly for sets of measurements. The system with the native OVA, a weak immunogen, showed only negligible AF compared with 85% measured for the immunogenic chlorinated OVA. The AF values varied with the tip-macrophage contact time and loading velocity. Blocking of the receptors by the chlorinated OVA was also confirmed. The developed approach can be also used to study other ligand-receptor interactions in poorly defined biological systems with intrinsically broad distribution of the rupture forces, thus opening new fields for AFM-based recognition on molecular level.

Macrophage-related diseases of the gut: a pathologist's perspective

The resident macrophages of the gastrointestinal tract represent the largest population of macrophages in the human body and are usually located in the subepithelial lamina propria. This strategic location guarantees a first-line defense to the huge numbers of potentially harmful bacteria and antigenic stimuli that are present in the intestinal lumen. In non-inflamed mucosa, macrophages phagocytose and kill microbes in the absence of an inflammatory response. However, in the event of an epithelial breach and/or microbial invasion, new circulating monocytes and lymphocytes will be recruited to the damaged area of the gut, which will result in the secretion of proinflammatory mediators and engage a protective inflammatory response. Although macrophages are usually not conspicuous in normal mucosal samples of the gut, they can easily be detected when they accumulate exogenous particulate material or endogenous substances or when they become very numerous. These events will mostly occur in pathologic conditions, and this review presents an overview of the diseases which are either mediated by or affecting the resident macrophages of the gut.

CD163 and its expanding functional repertoire

Macrophages are key players of the immune system and express a variety of surface receptors. CD163 is one such receptor which belongs to the scavenger receptor cysteine-rich super family (SRCR-SF) class B. It has four isoforms which differ in the structure of their cytoplasmic domains and putative phosphorylation sites. Expression of CD163 is tightly regulated with a general tendency of anti-inflammatory signals to induce its synthesis, while pro-inflammatory signals downregulate its expression. Previously the molecule has been shown to act as a receptor for hemoglobin-haptoglobin complexes. However, it also plays a crucial role in the control of inflammatory processes by induction of anti-inflammatory pathways. Soluble CD163, which is generated via ectodomain shedding, serves as a potential diagnostic tool in a variety of disease states, such as inflammation, atherosclerosis, transplant rejection and carcinoma. Recently, CD163 has been identified as a promising target for cell directed therapy. In this review we aim to summarize the current knowledge of CD163.

Function modification of SR-PSOX by point mutations of basic amino acids

Background

Atherosclerosis (AS) is a common cardiovascular disease. Transformation of macrophages to form foam cells by internalizing modified low density-lipoprotein (LDL) via scavenger receptor (SR) is a key pathogenic process in the onset of AS. It has been demonstrated that SR-PSOX functions as either a scavenger receptor for uptake of atherogenic lipoproteins and bacteria or a membrane-anchored chemokine for adhesion of macrophages and T-cells to the endothelium. Therefore, SR-PSOX plays an important role in the development of AS. In this study the key basic amino acids in the chemokine domain of SR-PSOX have been identified for its functions.

Results

A cell model to study the functions of SR-PSOX was successfully established. Based on the cell model, a series of mutants of human SR-PSOX were constructed by replacing the single basic amino acid residue in the non-conservative region of the chemokine domain (arginine 62, arginine 78, histidine 80, arginine 82, histidine 85, lysine 105, lysine 119, histidine 123) with alanine (designated as R62A, R78A, H80A, R82A, H85A, K105A, K119A and H123A, respectively). Functional studies showed that the mutants with H80A, H85A, and K105A significantly increased the activities of oxLDL uptake and bacterial phagocytosis compared with the wild-type SR-PSOX. In addition, we have also found that mutagenesis of either of those amino acids strongly reduced the adhesive activity of SR-PSOX by using a highly non-overlapping set of basic amino acid residues.

Conclusion

Our study demonstrates that basic amino acid residues in the non-conservative region of the chemokine domain of SR-PSOX are critical for its functions. Mutation of H80, H85, and K105 is responsible for increasing SR-PSOX binding with oxLDL and bacteria. All the basic amino acids in this region are important in the cells adhesion via SR-PSOX. These findings suggest that mutagenesis of the basic amino acids in the chemokine domain of SR-PSOX may contribute to atherogenesis.

The effect of surface topography on early NFκB signaling in macrophages

Surface topography modulates macrophage expression of pro-inflammatory cytokines through triggering of a number of different signaling pathways. In this article, we investigated the early activation of the NFκB pathway in RAW 264.7 macrophages in response to four surface topographies: mechanically polished (PO), coarse sand blasted (CB), acid etched (AE), and sandblasted and acid etched (SLA). We found that activation of the NFκB pathway was topography dependent. The PO and CB surfaces showed the highest level of activation, followed by the AE, then the SLA. Addition of suboptimal stimulatory concentrations of lipopolysaccharide (LPS) enhanced the response. Second, we determined that topography dependent cell signaling occurred in the absence of fetal bovine sera in the media. Third, we demonstrated that disruption of the lipid rafts by removal of cholesterol from cells in suspension using methyl β cyclodextrin (MβCD) affected signaling through the NFκB pathway and transcription of the pro-inflammatory cytokine IL-1 β, but did not affect cell adhesion, spreading or morphology. The number of macrophages adhered to the surfaces after 30 min followed the order PO, CB, AE, and SLA. In conclusion, our study suggests that one mechanism by which surface topography modulates activation of the NFκB pathway is through cholesterol-enriched raft-associated adhesive/signaling structures.

Intestinal macrophages and response to microbial encroachment

Macrophages in the gastrointestinal mucosa represent the largest pool of tissue macrophages in the body. In order to maintain mucosal homeostasis, resident intestinal macrophages uniquely do not express the lipopolysaccharide (LPS) co-receptor CD14 or the IgA (CD89) and IgG (CD16, 32, and 64) receptors, yet prominently display Toll-like receptors (TLRs) 3-9. Remarkably, intestinal macrophages also do not produce proinflammatory cytokines in response to TLR ligands, likely because of extracellular matrix (stromal) transforming growth factor-β (TGF-β) dysregulation of nuclear factor (NF)-κB signal proteins and, via Smad signaling, expression of IκBα, thereby inhibiting NF-κB-mediated activities. Thus, in noninflamed mucosa, resident macrophages are inflammation anergic but retain avid scavenger and host defense function, an ideal profile for macrophages in close proximity to gut microbiota. In the event of impaired epithelial integrity during intestinal infection or inflammation, however, blood monocytes also accumulate in the lamina propria and actively pursue invading microorganisms through uptake and degradation of the organism and release of inflammatory mediators. Consequently, resident intestinal macrophages are inflammation adverse, but when the need arises, they receive assistance from newly recruited circulating monocytes.

Endothelial lipase promotes apolipoprotein AI-mediated cholesterol efflux in THP-1 macrophages

OBJECTIVE

Endothelial lipase (EL) is expressed by macrophages within atherosclerotic lesions. We investigated the influence of EL expression on cholesterol efflux in macrophages.

METHODS AND RESULTS

The present study used lentivirus to introduce either EL shRNA for loss-of-function studies or EL cDNA for gain-of-function studies to investigate the role of EL in apoAI-mediated cholesterol efflux. ApoAI-mediated cholesterol efflux was decreased after EL suppression, but increased with EL overexpression in free cholesterol labeled and acLDL loaded THP-1 macrophages. Similar findings were observed in THP-1 macrophages after exogenous EL addition and in transfected 293 cells. EL-related apoAI-mediated cholesterol efflux decreased after treatment with heparin or catalytic inactivation (S149A mutation or tetrahydrolipstatin) alone, and completely inhibited in combination. Furthermore, EL expression did not change ABCA1 expression, but was positively correlated with apoAI binding to macrophages and 293 cells. This effect was mitigated after heparin treatment but not influenced by catalytic inactivation via tetrahydrolipstatin or the S149A mutation. Moreover, EL expression was positively associated with lysophosphatidylcholine production and inversely with phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin levels. Lysophosphatidylcholine treatment dose-dependently stimulated apoAI-mediated cholesterol efflux in THP-1 macrophages.

CONCLUSIONS

EL appears to promote apoAI-mediated cholesterol efflux through catalytic and noncatalytic-dependent mechanisms.

Mechanisms of adaptive angiogenesis to tissue hypoxia

Angiogenesis is mostly an adaptive response to tissue hypoxia, which occurs under a wide variety of situations ranging from embryonic development to tumor growth. In general, angiogenesis is dependent on the accumulation of hypoxia inducible factors (HIFs), which are heterodimeric transcription factors of alpha and beta subunits. Under normoxia, HIF heterodimers are not abundantly present due to oxygen dependent hydroxylation, polyubiquitination, and proteasomal degradation of alpha subunits. Under hypoxia, however, alpha subunits are stabilized and form heterodimers with HIF-1beta which is not subject to oxygen dependent regulation. The accumulation of HIFs under hypoxia allows them to activate the expression of many angiogenic genes and therefore initiates the angiogenic process. In recent years, however, it has become clear that various other mechanisms also participate in fine tuning angiogenesis. In this review, I discuss the relationship between hypoxia and angiogenesis under five topics: (1) regulation of HIF-alpha abundance and activity by oxygen tension and other conditions including oxygen independent mechanisms; (2) hypoxia-regulated expression of angiogenic molecules by HIFs and other transcription factors; (3) responses of vascular cells to hypoxia; (4) angiogenic phenotypes due to altered HIF signaling in mice; and (5) role of the HIF pathway in pathological angiogenesis. Studies discussed under these topics clearly indicate that while mechanisms of oxygen-regulated HIF-alpha stability provide exciting opportunities for the development of angiogenesis or anti-angiogenesis therapies, it is also highly important to consider various other mechanisms for the optimization of these procedures.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Comparative toxicity of fatty acids on a macrophage cell line (J774)

In the present study, the cytotoxicity of palmitic, stearic, oleic, linoleic, arachidonic, docosahexaenoic and eicosapentaenoic acids on a macrophage cell line (J774) was investigated. The induction of toxicity was investigated by changes in cell size, granularity, membrane integrity, DNA fragmentation and phosphatidylserine externalization by using flow cytometry. Fluorescence microscopy was used to determine the type of cell death (Acridine Orange/ethidium bromide assay). The possible mechanisms involved were examined by measuring mitochondrial depolarization, lipid accumulation and PPARgamma (peroxisome-proliferator-activated receptor gamma) activation. The results demonstrate that fatty acids induce apoptosis and necrosis of J774 cells. At high concentrations, fatty acids cause macrophage death mainly by necrosis. The cytotoxicity of the fatty acids was not strictly related to the number of double bonds in the molecules: palmitic acid>docosahexaenoic acid>stearic acid=eicosapentaenoic acid=arachidonic acid>oleic acid>linoleic acid. The induction of cell death did not involve PPARgamma activation. The mechanisms of fatty acids to induce cell death involved changes in mitochondrial transmembrane potential and intracellular neutral lipid accumulation. Fatty acids poorly incorporated into triacylglycerol had the highest toxicity.

The Di-Leucine Motif Contributes to Class A Scavenger Receptor-Mediated Internalization of Acetylated Lipoproteins

Objective— The di-leucine motif exists in the intracellular domains of certain cell surface receptors, participating in the receptor-mediated endocytosis. The present study was aimed at determining the role of the di-leucine motif in class A scavenger receptor (SR-A)-mediated ligand endocytosis.

Methods and Results— cDNA coding for a mutant (SR-A mutant N3132LM) with deletion of the di-leucine structure was transfected into Chinese hamster ovary (CHO) cells. Compared with wild-type SR-A–expressing cells, the cells expressing the SR-A mutant N3132LM showed a significant decrease in uptake but almost no change in binding of the SR-A ligand acetylated low-density lipoprotein (AcLDL). Western blot analysis revealed coimmunoprecipitation of SR-A mutant and clathrin from the lysates of the mutant but not wild-type CHO cells, suggesting that AcLDL-bound SR-A mutant N3132LM is associated with the clathrin-coated pit of cellular membrane. Removal of the first 27 amino acid residues from the SR-A N-terminus further reduced AcLDL uptake by the cells with the di-leucine motif mutation.

Conclusions— The di-leucine motif of SR-A intracellular domain contributes to the SR-A–mediated cellular internalization of AcLDL. Di-leucine pair exists in the cytoplasmic domain of class A scavenger receptor. The cells expressing di-leucine mutants showed decreased uptake and unchanged binding of AcLDL. The di-leucine pair was not associated to coated pits. It suggests that di-leucine motif acts as a signal sequence to mediate SR-A into cell.

The macrophage scavenger receptor CD163

Mature tissue macrophages form a first line of defense to recognize and eliminate potential pathogens; these specialized cells are capable of phagocytosis, degradation of self and foreign materials, establishment of cell-cell interactions, and the production of inflammatory mediators. Mature tissue macrophages express a variety of receptors, including the scavenger receptor cystein-rich (SRCR) superfamily members. CD163 is a member of the SRCR family class B and is expressed on most subpopulations of mature tissue macrophages. The best characterized function of CD163, which is essentially a homeostatic one, is related to the binding of Hemoglobin:Haptoglobin complexes. Furthermore, it has been suggested that CD163 positive macrophages or the soluble form of CD163 plays a role in the resolution of inflammation, as they are found in high numbers in inflamed tissue.

Intestinal macrophages: unique effector cells of the innate immune system

The gastrointestinal mucosa is the largest reservoir of macrophages in the body. These important effector cells are derived from blood monocytes that are recruited to the lamina propria by endogenous chemoattractants in the non-inflamed mucosa and by inflammatory chemokines and bacterial products during inflammation. In the non-inflamed mucosa, newly recruited pro-inflammatory monocytes are exposed to lamina propria stromal (extracellular matrix) factors that induce phenotypic and functional differentiation into non-inflammatory macrophages. As a consequence of this differentiation, resident lamina propria macrophages are strikingly downregulated for the expression of innate response receptors, such as the receptors for lipopolysaccharide, immunoglobulin G (IgG), and IgA, and the production of pro-inflammatory cytokines, including interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor-alpha. Despite downregulated pro-inflammatory function, strong phagocytic and bactericidal activities remain intact. Thus, in the non-inflamed intestinal mucosa, lamina propria macrophages are non-inflammatory but retain avid scavenger and host defense functions, a unique but ideal phenotype and functional profile for effector cells in close proximity to immunostimulatory microorganisms and products.

R-MC46 monoclonal antibody stimulates adhesion and phagocytosis by rat macrophages

BACKGROUND

In our previous experiments it was shown that R-MC46 monoclonal antibody (mAb), produced at our Institute, stimulated homotypic aggregation of rat granulocytes and production ofproinflammatory cytokines. The aim of this study was to examine antigen expression and function, recognized by R-MC46 mAb on macrophages.

METHODS

The expression of R-MC46 antigen on thymic and peritoneal macrophages was investigated using immunocytochemistry and flow cytometry methods. Its biochemical characterization was performed by Western blot. The ability of R-MC46 mAb to modulate adhesion and phagocytosis by macrophages was studied by using co-culture experiments with autologous thymocytes.

RESULTS

R-MC46 mAb stained thymic macrophages more strongly than peritoneal macrophages. After in vivo treatment of peritoneal macrophages with Pristane, a significant up-regulation of the R-MC46 antigen expression was observed Western blot analysis showed that the mAb recognized a low molecular weight antigen of about 5.5 kDa. R-MC46 mAb significantly enhanced binding and phagocytosis of thymocytes by both thymic and peritoneal macrophages. These processes were completely blocked by WT.3 (anti-CD18) mAb. The stimulation of binding thymocyte to macrophages was higher with the use of thymic macrophages,while the phagocytosis of these cells was higher in the presence of peritoneal macrophages.

CONCLUSION

R-MC46 mAb recognized a new molecule expressed by rat macrophages. The antigen is most probably involved in 82 integrin-mediated adhesion and phagocytosis, as well as proinflammatory functions of macrophages.

Effect of titanium surface topography on macrophage activation and secretion of proinflammatory cytokines and chemokines

The macrophage has a major role in normal wound healing and the reparative process around implants. Murine macrophage-like cells RAW 264.7 were used to investigate the effect of titanium surfaces on macrophage activation and secretion of proinflammatory cytokines [interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha] and chemokines (monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha). Four topographies were used: those produced by mechanically polishing, coarse sand blasting, acid etching, and sandblasting and acid etching (SLA). Macrophages were plated on the four titanium surfaces at a population density of 5 x 10(5) cells/mL/well. Tissue culture plastic and tissue culture plastic plus lipopolysaccharide (LPS) served as negative and positive control, respectively. In addition, all surfaces were tested for their effects on macrophages in the presence of LPS. Supernatants were collected for assays after 6, 24, and 48 h and the numbers of macrophages attached to the surfaces were quantified using the DAPI (4,6-di-amidino-2-phenylindole) assay. Cytokine and chemokine levels were measured with sandwich enzyme-linked immunosorbent assays. Statistical comparison between the surfaces and the controls was determined by using the two-way analysis of variance including interaction effect (two tailed and p < or = 0.05). Unstimulated macrophages increased their secretion of the proinflammatory cytokine (TNF-alpha) when attached to rough surfaces (acid etching and SLA, p < or = 0.05). In macrophages stimulated with LPS, the roughest surface SLA produced higher levels of IL-1 beta, IL-6, and TNF-alpha at 24 and 48 h than all other surfaces (p < or = 0.05). Surface topography also modulated the secretion of the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha by macrophages. Unstimulated macrophages attached to the SLA surface down-regulated their production of chemokines (p < or = 0.05) whereas LPS-stimulated macrophages attached to the SLA surface up-regulated their production (p < or = 0.05). Moreover, the SLA surface was found to act synergistically with LPS as well as the combination of blasting and etching features of the SLA surface resulted in significant release of proinflammatory cytokines and chemokines by stimulated macrophages at 24 and 48 h (p < or = 0.05). This in vitro study has demonstrated that surface topography, in particular the SLA surface, modulated expression of proinflammatory cytokines and chemokines by macrophages in a time-dependent manner.

Establishment of an ex vivo model of monocytes-derived macrophages differentiated from peripheral blood mononuclear cells (PBMCs) from HIV-1 transgenic rats

It has been developed an HIV type 1 transgenic rat model (HIV-1 Tg Rat) which contains a gag-pol-deleted HIV-1 provirus regulated by the viral LTR promoter. Although it harbors a non infectious provirus, efficient viral expression occurs in different tissues and disease manifestations as well as immune-response alterations and pathologies similar to humans can be observed. Regulation of HIV-1 expression is influenced by various cellular factors and it is well known that macrophages are one of the major reservoir of HIV-1 infection and a vehicle for virus spread to other tissues. Purpose of our work was to establish an antigen presenting cells (monocyte-derived macrophages, MDM) ex vivo model from these HIV-1 transgenic rats. This model can be used to study function of HIV-infected MDM and their behavior like HIV-1 reservoir. Ultimately, these studies may be helpful in defining approaches to control HIV-1 spread.

The mannose receptor in the brain

The mannose receptor is a transmembrane glycoprotein mainly expressed by macrophages, that specifically binds to mannosylated molecules and mediates their endocytosis. Known ligands of the receptor are lysosomases and various pathogens. Ligand specificity and cellular distribution provide the mannose receptor with a very important role in homeostasis and in the immune response. Expression of the mannose receptor has recently been demonstrated in the brain. Astrocytes and microglia, two types of glial cells that can be turned into immune-competent cells, are the main site of expression in vivo and in vitro. The mannose receptor mediates in vitro pinocytosis by astrocytes and microglia and phagocytosis by microglia. Expression and endocytic activities of the mannose receptor in these cells are regulated by various cytokines. Based on our current knowledge on mannose receptor activities in brain cells, on its regional and temporal expression in that organ, and on its putative ligands therein, the possible involvement of the mannose receptor in brain homeostasis, neuronal functions, and brain defense is discussed.

Cellular inflammatory response to porcine collagen membranes

OBJECTIVES

The purpose of this study was to assess local inflammatory changes associated with the implantation of three different porcine collagen membranes having potential use in periodontal regeneration.

METHODS

Materials were implanted subcutaneously into prepared sites along the dorsal skin surface of 60 female Wistar rats. Saline and turpentine were used as negative and positive controls, respectively. Animals were killed and biopsies obtained after 3 d, and at 1, 2, 4, 6, and 8 weeks after membrane implantation. A panel of six monoclonal antibodies was used to identify circulating monocytes (ED1), resident tissue macrophages (ED2), lymphoid macrophages (ED3), Ia-antigen expression (OX6), T-lymphocytes (OX19), and B-lymphocytes (OX33). Cells identified by each antibody were subjected to quantitative immunocytochemistry to compare any differences present among groups. Sera obtained 8 weeks after grafting were used in immunoblotting assays to detect the presence of systemic antiporcine antibodies.

RESULTS

We found that the mononuclear cell subsets associated with implantation of porcine collagen membranes were similar to those obtained with saline administration. On the other hand, the use of turpentine resulted in an inflammatory infiltrate characterized by significantly higher numbers of all six monoclonal cell subsets at all time periods evaluated, compared to either saline or any of the membranes (P < 0.001).

CONCLUSIONS

The collagen membranes do not appear to be associated with a significant local inflammatory response, nor a systemic immune response, and thus appear to be well tolerated, rendering them useful in periodontal regeneration.

Heterogeneity in control of mRNA stability by AU-rich elements

AU-rich elements (AREs), located in the 3'-untranslated region of unstable cytokine and chemokine mRNAs, promote rapid decay of otherwise stable mRNAs and may mediate selective mRNA stabilization in response to stimulation with interleukin-1 (IL-1). AREs vary considerably, however, in both size and sequence context. To assess the heterogeneity involved in control of mRNA stability by ARE motifs, human mRNA sequences from IL-1alpha-stimulated HEK293 cells and T98G cells were screened for either instability or stability using both cDNA (950 ARE containing sequences) and Affymetrix oligonucleotide (U95Av2 GeneChip) array analysis. Although ARE-containing mRNAs exhibited a broad range of stability, IL-1alpha promoted stability in a subset of mRNAs that were unstable when transcriptionally induced by tumor necrosis factor alpha. Stabilization of granulocyte/macrophage-colony stimulating factor and IL-8 mRNAs by IL-1alpha was achieved only after 2 h of stimulation, required ongoing protein synthesis, and depended on the activation of p38 MAPK. In contrast, stabilization of Gro3 mRNA in response to IL-1alpha was achieved immediately and was insensitive to inhibitors of protein synthesis and p38 MAPK activation. In concert, these findings demonstrate that ARE sequences are functionally heterogeneous; only a subset of unstable mRNAs is sensitive to stabilization by IL-1alpha. Moreover, IL-1alpha promotes stabilization of unstable mRNAs through distinct mechanistic pathways that distinguish between specific mRNA sequences.

Differential expression of platelet-activating factor acetylhydrolase in macrophages and monocyte-derived dendritic cells

Although macrophages (Mphi) and monocyte-derived dendritic cells (MDDC) come from a common precursor, they are distinct cell types. This report compares the two cell types with respect to the metabolism of platelet-activating factor (PAF), a biologically active lipid mediator. These experiments were prompted by our studies of localized juvenile periodontitis, a disease associated with high IgG2 production and a propensity of monocytes to differentiate into MDDC. As the IgG2 Ab response is dependent on PAF, and MDDC selectively induce IgG2 production, we predicted that PAF levels would be higher in MDDC than in Mphi. To test this hypothesis, human MDDC were prepared by treating adherent monocytes with IL-4 and GM-CSF, and Mphi were produced by culture in M-CSF. Both Mphi and MDDC synthesized PAF; however, MDDC accumulated significantly more of this lipid. We considered the possibility that PAF accumulation in MDDC might result from reduced turnover due to lower levels of PAF acetylhydrolase (PAFAH), the enzyme that catabolizes PAF. Although PAFAH increased when monocytes differentiated into either cell type, MDDC contained significantly less PAFAH than did Mphi and secreted almost no PAFAH activity. The reduced levels of PAFAH in MDDC could be attributed to lower levels of expression of the enzyme in MDDC and allowed these cells to produce PGE(2) in response to exogenous PAF. In contrast, Mphi did not respond in this manner. Together, these data indicate that PAF metabolism may impinge on regulation of the immune response by regulating the accessory activity of MDDC.

Adoptive immunotherapy for superficial bladder cancer with autologous macrophage activated killer cells

PURPOSE

We assessed the efficacy and safety of adoptive immunotherapy administered to 17 patients with TaGIII or recurrent TaGII superficial bladder cancer following transurethral tumor resection.

MATERIALS AND METHODS

Macrophage activated killer (MAK) cells were obtained from autologous mononuclear cells harvested by apheresis, after in vitro culture for 7 days and activation with interferon-gamma on the last day of culture. The patients received 6 weekly intravesical infusions of approximately 2 x 10(8) cells each. Additionally, 5 patients received 2 or 3 more infusions at 3-month intervals. Each patient was followed for 1 year or until tumor recurrence, whichever came first.

RESULTS

A total of 112 intravesical infusions were performed. During the 12-month followup period 8 patients experienced 11 common toxicity criteria grade 1 or grade 2 adverse events considered possibly related to protocol. No clinically relevant grade 1 or 2 laboratory test results were reported while the patients received treatment. In 17 patients 8 tumors recurred compared to 34 recurrences during the year before the first MAK cell infusion. This difference was highly significant (p </=0.0005).

CONCLUSIONS

The promising efficacy and safety results of this study and the fact that the MAK cell treatment regimen proved feasible should encourage initiation of further large scale studies to confirm these data.

CD8 T cell-mediated killing of Cryptococcus neoformans requires granulysin and is dependent on CD4 T cells and IL-15

Granulysin is located in the acidic granules of cytotoxic T cells. Although the purified protein has antimicrobial activity against a broad spectrum of microbial pathogens, direct evidence for granulysin-mediated cytotoxicity has heretofore been lacking. Studies were performed to examine the regulation and activity of granulysin expressed by CD8 T cells using Cryptococcus neoformans, which is one of the most common opportunistic pathogens of AIDS patients. IL-15-activated CD8 T cells acquired anticryptococcal activity, which correlated with the up-regulation of granulysin. When granules containing granulysin were depleted using SrCl(2,) or when the gene was silenced using 21-nt small interfering RNA duplexes, the antifungal effect of CD8 T cells was abrogated. Concanamycin A and EGTA did not affect the antifungal effect, suggesting that the activity of granulysin was perforin independent. Following stimulation by the C. neoformans mitogen, CD8 T cells expressed granulysin and acquired antifungal activity. This activity required CD4 T cells and was dependent upon accessory cells. Furthermore, IL-15 was both necessary and sufficient for granulysin up-regulation in CD8 T cells. These observations are most consistent with a mechanism whereby C. neoformans mitogen is presented to CD4 T cells, which in turn activate accessory cells. The resultant IL-15 activates CD8 T cells to express granulysin, which is responsible for antifungal activity.

Opinion: Interpretation of the complexity of innate immune responses by functional genomics

Understanding how the immune system is regulated and responds to pathogens will require whole-system approaches, because the study of single immunological parameters has, so far, been unable to unlock immune-system complexity. Global transcription analysis using microarray technologies provides a new approach to the description of complex biological phenomena. Here, we discuss insights into innate immunity that have been provided by genome-wide approaches and their impact on the interpretation of immune-system complexity.

The use of cytochemistry, immunophenotyping, flow cytometry, and in vitro differentiation to determine the ontogeny of a canine monoblastic leukemia

We evaluated the utility of cytochemistry, immunophenotyping, flow cytometry, and in vitro culture with forced differentiation of leukemic cells as diagnostic aids to identify the malignant cell ontogeny in a dog with leukemia. A tentative diagnosis of monoblastic leukemia was established by microscopic examination of Romanowsky-stained blood smears and bone marrow aspirate smears. This diagnosis also was supported by the light scatter signature that identified the blast cells as large, non-granular monocytic cells using a CellDyn 3500 automated hematology analyzer; as well as by the detection of N-butyrate esterase and the lack of choloroacetate esterase or leukocyte peroxidase by cytochemical staining. Subsequently, leukemic cells were isolated from the dog's peripheral blood and placed into tissue culture or cryopreserved. The leukemic cells grew in suspension cultures and proliferated spontaneously for up to 4 days. By day 7, proliferation was negligible. Upon culture with conditioned supernatant using mitogen-stimulated human T cells as a source of cytokines, an increased proportion of cells entered S phase by day 2 of culture; however, proliferation declined markedly by day 4, at which time the cells had apparently differentiated to adherent, vacuolated macrophages. The cytokine-stimulated leukemic cells were positive for the monocyte/macrophage specific markers alpha-1-antitrypsin, alpha-1-antichymotrypsin, lysozyme, CD14, MHC class II, and calprotectin, an antigen found in differentiated macrophages and granulocytes. Despite the strong tendency of the leukemic cells towards monocytic differentiation, our results suggested that they retained some features of a myelomonocytic precursor. These data show that cytochemistry, immunophenotyping, flow cytometry, and in vitro differentiation of canine leukemia cells are useful tools for confirming the lineage of malignant hematopoietic cells.

Reduced tissue macrophage population in the lung by anticancer agent cyclophosphamide: restoration by local granulocyte macrophage-colony-stimulating factor gene transfer

Granulocytopenia is thought to be the sole mechanism underlying the increased susceptibility to bacterial infection in hosts with anticancer chemotherapy. Little is known about the functional state of tissue macrophage populations in such hosts. Using a model of chemotherapy-induced leukopenia, the number and function of alveolar macrophages (AMS) were examined during and after multiple injections of an anticancer agent, cyclophosphamide (CP). Although CP quickly reduced peripheral blood leukocytes, the number of these cells rebounded quickly 3 to 4 days after the withdrawal of CP. Accompanying blood leukopenia was a profound reduction in the number of AMs. Contrary to the rapid onset of blood leukopenia, tissue macrophage deficiency was a more chronic process that worsened gradually as the CP regimen continued. Of importance, in contrast to blood leukopenia, which restored itself shortly after CP withdrawal, tissue macrophage deficiency was not immediately self-recoverable in spite of a restored number of circulating leukocytes. Although AMS had a decreased ability to proliferate during, but not after, the CP regimen, these cells retained a normal ability to release tumor necrosis factor-alpha and nitric oxide. To identify the potential therapeutics for recovering macrophages, a gene vector expressing granulocyte macrophage-colony-stimulating factor (GM-CSF) was delivered either systemically or locally. GM-CSF transgene was able to expand macrophage populations only when delivered to the lung after, but not during, the CP regimen. This study thus identifies tissue macrophage deficiency as a mechanism of weakened innate immunity by chemotherapy and suggests the usefulness of topical GM-CSF transgene expression for restoring innate immunity in the lung.

A macrophage protein, Ym1, transiently expressed during inflammation is a novel mammalian lectin

Oral infections of mice with Trichinella spiralis induce activation of peritoneal exudate cells to transiently express and secrete a crystallizable protein Ym1. Purification of Ym1 to homogeneity was achieved. It is a single chain polypeptide (45 kDa) with a strong tendency to crystallize at its isoelectric point (pI 5.7). Co-expression of Ym1 with Mac-1 and scavenger receptor pinpoints macrophages as its main producer. Protein microsequencing data provide information required for full-length cDNA cloning from libraries constructed from activated peritoneal exudate cells. A single open reading frame of 398 amino acids with a leader peptide (21 residues) typical of secretory protein was deduced and later deposited in GenBank (accession number M94584) in 1992. By means of surface plasmon resonance analyses, Ym1 has been shown to exhibit binding specificity to saccharides with a free amine group, such as GlcN, GalN, or GlcN polymers, but it failed to bind to other saccharides. The interaction is pH-dependent but Ca2+ and Mg2+ ion-independent. The binding avidity of Ym1 to GlcN oligosaccharides was enhanced by more than 1000-fold due to the clustering effect. Specific binding of Ym1 to heparin suggests that heparin/heparan sulfate may be its physiological ligand in vivo during inflammation and/or tissue remodeling. Although it shares approximately 30% homology with microbial chitinases, no chitinase activity was found associated with Ym1. Genomic Southern blot analyses suggest that Ym1 may represent a member of a novel lectin gene family.

Molecular cloning and expression pattern of porcine myeloid DAP12-associating lectin-1

DAP12 is an ITAM-bearing membrane protein that is associated with activating receptors in natural killer cells, granulocytes, macrophages, and monocytes. Myeloid DAP12-associating lectin-1 (MDL-1) is a type II membrane protein that associates with DAP12. In this study, we report the molecular cloning of two isoforms of porcine MDL-1 cDNA from pulmonary alveolar macrophages. The porcine MDL-1 short form has 165 amino acids and 70% sequence identity with the mouse MDL-1 short form. The long form has 20 more amino acids in the stalk region and 71% sequence identity with human MDL-1 and 67% with the mouse MDL-1 long form. Porcine MDL-1 contains a conserved lysine in the transmembrane domain. There are six putative N-linked glycosylation sites in the MDL-1 long form. MDL-1 transcripts were detected exclusively in macrophages and monocytes by RT-PCR. When transfected into 293 cells, porcine MDL-1 is expressed on the cell surface associated with DAP12.

Immunology of trauma

Systemic inflammation involves a large number of mediators and effector mechanisms. One approach to understanding systemic inflammation is to interpret the nature of the response based on the effector mechanisms that are observed. An alternative approach is to consider these effector responses in the context of our current understanding of immunoregulation. The aim of this article is to provide an overview of the immune response and discuss the mechanisms of immunoregulation in order to provide non-immunologists with a framework for understanding the normal and aberrant immune responses that can be precipitated by major trauma. The clinical manifestations of the inflammatory response to major trauma resemble those observed after other significant insults (surgery, burns, and pancreatitis). Furthermore, the clinical manifestations, changes in serum proteins, and pattern of immune activation point to the presence of infection, yet proof of a contribution by infection to the pathogenesis by infection remains elusive. Although inflammation dominates the early phase of the response, there is often evidence of a paradoxical combination of inflammation and immunosuppression later on. Consideration of the proinflammatory cascades, and the contribution of the innate immune system, helps explain why the clinical picture after major trauma may resemble other clinical states. It also explains the counter-regulatory response, which normally acts to downregulate inflammation, but may cause immunosuppression in the face of persistent inflammation after major trauma.

Unilineage hematopoietic differentiation in bulk and single cell culture

The rarity of hematopoietic stem and progenitor cells (HSCs, HPCs) has hampered the analysis of cellular and molecular mechanisms underlying early hematopoiesis. Methodology for HPC purification has partially offset this limitation. A further hurdle has been represented by the heterogeneity of the analyzed HPC/precursor populations: recently, development of unilineage HPC differentiation cultures has provided homogeneous populations of hematopoietic cells, particularly in the early differentiation state, i.e., populations pertaining to a single lineage and a restricted stage of differentiation/maturation, but sufficiently large for cellular/molecular analysis. This report focuses on the development and characterization of the unilineage HPC differentiation culture systems. A section is devoted to selected cellular and molecular mechanisms underlying hematopoiesis, which have been investigated by the HPC unilineage culture approach. Finally, recent advances in the development of HPC unilineage cultures at single cell level are discussed.