Macrophages overexpressing tartrate-resistant acid phosphatase show altered profile of free radical production and enhanced capacity of bacterial killing

TRAPping the effects of tobacco smoking: the regulation and function of Acp5 expression in lung macrophages

Tartrate-resistant acid phosphatase [TRAP, gene acid phosphatase 5 (Acp5; gene name for TRAP)] is highly expressed in alveolar macrophages with proposed roles in lung inflammation and lung fibrosis development. We previously showed that its expression and activity are higher in lung macrophages of smokers and patients with chronic obstructive pulmonary disease (COPD), suggesting involvement in smoke-induced lung damage. In this study, we explored the function of TRAP and regulation of its different mRNA transcripts (Acp5 201-206) in lung tissue exposed to cigarette smoke to elucidate its function in alveolar macrophages. In mice exposed to cigarette smoke or air for 4-6 wk, higher Acp5 mRNA expression in lung tissue after smoking was mainly driven by transcript Acp5-202, which originates from macrophages. The expression of Acp5-202 correlated with transcription factors previously found to drive proliferation of macrophages. Treating fetal liver progenitor-derived alveolar-like macrophages [Max Planck Institute (MPI; macrophages derived from fetal liver progenitors) macrophages] with cigarette smoke extract resulted in more proliferation compared with nontreated cells. In contrast, Acp5-deficient MPI macrophages and MPI macrophages treated with a TRAP inhibitor proliferated significantly less than control macrophages. Mechanistically, this lack of proliferation after TRAP inhibition was associated with higher presence of phosphorylated Beta-catenin (β-catenin; a signaling protein) compared with nontreated controls. Phosphorylation of β-catenin is known to mark it for ubiquitination and degradation by the proteasome, preventing its activity in promoting cell proliferation. In conclusion, our findings provide strong evidence for TRAP stimulating alveolar macrophage proliferation by dephosphorylating β-catenin. By driving proliferation, TRAP likely helps sustain alveolar macrophage populations during smoke exposure, either compensating for their loss due to smoking or increasing their numbers to better manage smoke-induced damage.NEW & NOTEWORTHY This study has uncovered that the enzyme tartrate-resistant acid phosphatase (TRAP) is crucial for alveolar macrophage proliferation through a β-catenin-dependent pathway. Importantly, TRAP influences this important ability of alveolar macrophages through the Acp5-202 mRNA transcript. The increase in TRAP expression following smoke exposure suggests that it plays a key role in promoting cell renewal, potentially helping to mitigate smoke-induced lung damage.

A Synthetic Small Molecule, LGM2605: A Promising Modulator of Increased Pro-Inflammatory Cytokine and Osteoclast Differentiation by Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin

Our research explores the interplay between Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) and the host's inflammatory response in molar/incisor pattern periodontitis (MIPP). Cdt disrupts phosphatidylinositol-3,4,5-triphosphate (PIP3) signaling, influencing cytokine expression through canonical and non-canonical inflammasome activation as well as nuclear factor-κB (NF-κB) activation, leading to inflammation in MIPP. THP-1 differentiated macrophages (TDMs) exposed to Cdt exhibited an upregulation of pro-inflammatory genes and subsequent cytokine release. We analyzed the ability of a small molecule therapeutic, LGM2605, known for its anti-inflammatory properties, to reduce pro-inflammatory gene expression and cytokine release in Cdt-exposed and Aa-inoculated TDMs. LGM2605's mechanism of action involves inhibiting NF-κB while activating the Nrf2-transcription factor and antioxidants. Herein, we show that this small molecule therapeutic mitigates Cdt-induced pro-inflammatory cytokine expression and secretion. Our study also further defines Cdt's impact on osteoclast differentiation and maturation in MIPP. Cdt promotes increased TRAP+ cells, indicating heightened osteoclast differentiation, specific to Cdt's phosphatase activity. Cathepsin K levels rise during this process, reflecting changes in TRAP distribution between control and Cdt-treated cells. Exploring LGM2605's effect on Cdt-induced osteoclast differentiation and maturation, we found TRAP+ cells significantly reduced with LGM2605 treatment compared to Cdt alone. Upon LGM2605 treatment, immunocytochemistry revealed a decreased TRAP intensity and number of multinucleated cells. Moreover, immunoblotting showed reduced TRAP and cathepsin K levels, suggesting LGM2605's potential to curb osteoclast differentiation and maturation by modulating inflammatory cytokines, possibly involving Nrf2 activation. In summary, our research reveals the intricate connections between Cdt, pro-inflammatory cytokines, and osteoclast differentiation, offering novel therapeutic possibilities for managing these conditions.

Time-resolved single-cell transcriptomics defines immune trajectories in glioblastoma

Deciphering the cell-state transitions underlying immune adaptation across time is fundamental for advancing biology. Empirical in vivo genomic technologies that capture cellular dynamics are currently lacking. We present Zman-seq, a single-cell technology recording transcriptomic dynamics across time by introducing time stamps into circulating immune cells, tracking them in tissues for days. Applying Zman-seq resolved cell-state and molecular trajectories of the dysfunctional immune microenvironment in glioblastoma. Within 24 hours of tumor infiltration, cytotoxic natural killer cells transitioned to a dysfunctional program regulated by TGFB1 signaling. Infiltrating monocytes differentiated into immunosuppressive macrophages, characterized by the upregulation of suppressive myeloid checkpoints Trem2, Il18bp, and Arg1, over 36 to 48 hours. Treatment with an antagonistic anti-TREM2 antibody reshaped the tumor microenvironment by redirecting the monocyte trajectory toward pro-inflammatory macrophages. Zman-seq is a broadly applicable technology, enabling empirical measurements of differentiation trajectories, which can enhance the development of more efficacious immunotherapies.

Identification and Functional Analysis of Tartrate-Resistant Acid Phosphatase Type 5b (TRAP5b) in Oreochromis niloticus

Tartrate-resistant acid phosphatase type 5 (TRAP5) is an enzyme that is highly expressed in activated macrophages and osteoclasts and plays important biological functions in mammalian immune defense systems. In the study, we investigated the functions of tartrate-resistant acid phosphatase type 5b from Oreochromis niloticus (OnTRAP5b). The OnTRAP5b gene has an open reading frame of 975 bp, which encodes a mature peptide consisting of 302 amino acids with a molecular weight of 33.448 kDa. The OnTRAP5b protein contains a metallophosphatase domain with metal binding and active sites. Phylogenetic analysis revealed that OnTRAP5b is clustered with TRAP5b of teleost fish and shares a high amino acid sequence similarity with other TRAP5b in teleost fish (61.73-98.15%). Tissues expression analysis showed that OnTRAP5b was most abundant in the liver and was also widely expressed in other tissues. Upon challenge with Streptococcus agalactiae and Aeromonas hydrophila in vivo and in vitro, the expression of OnTRAP5b was significantly up-regulated. Additionally, the purified recombinant OnTRAP5b ((r)OnTRAP5) protein exhibited optimal phosphatase activity at pH 5.0 and an ideal temperature of 50 °C. The Vmax, Km, and kcat of purified (r)OnTRAP5b were found to be 0.484 μmol × min-1 × mg-1, 2.112 mM, and 0.27 s-1 with respect to pNPP as a substrate, respectively. Its phosphatase activity was differentially affected by metal ions (K+, Na+, Mg2+, Ca2+, Mn2+, Cu2+, Zn2+, and Fe3+) and inhibitors (sodium tartrate, sodium fluoride, and EDTA). Furthermore, (r)OnTRAP5b was found to promote the expression of inflammatory-related genes in head kidney macrophages and induce reactive oxygen expression and phagocytosis. Moreover, OnTRAP5b overexpression and knockdown had a significant effect on bacterial proliferation in vivo. When taken together, our findings suggest that OnTRAP5b plays a significant role in the immune response against bacterial infection in Nile tilapia.

Molecular characterization and functional analysis of tartrate-resistant acid phosphatase (ACP5) gene in red drum (Sciaenops ocellatus)

Tartrate-resistant acid phosphatase (ACP5) plays an important biological function in immune defense and is highly expressed in activated macrophages, osteoclasts and dendritic cells. In teleost, the functionality of ACP5 remains to be revealed. In this study, we cloned and identified SoACP5 from red drum (Sciaenops ocellatus) and analyzed its function in vivo and in vitro. The open reading frame of SoACP5 is 1002 bp in length, encoding 333 amino acids. SoACP5 shares high sequence identities (96.70%-49.25%) with ACP5 of other species. The SoACP5 mRNA was widely distributed in collected tissues of healthy red drum, and with the maximum in gills. The expression of SoACP5 increased significantly in vivo following challenge with Edwardsiella tarda. Moreover, the recombinant SoACP5 protein (rSoACP5) was purified with his-tag band resin columns, and confirmed to have phosphatase activity which was optimal at pH 5 and 55 °C. Various metal ions (K⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Cu²⁺, Fe²⁺ and Fe³⁺) have different effects on phosphatase activity. rSoACP5 induced the cellular proliferation of peripheral blood leukocytes. The over-expression and knockdown of SoACP5 in vivo had a significant effect on bacterial proliferation. Furthermore, both of the antibacterial activity and phosphatase activity were decreased when the reducedSoACP5 was oxidized by H₂O₂. In summary, the present study indicated that SoACP5 is likely involved in host defense against bacterial infection in S. ocellatus.

Towards understanding the cell surface phenotype, metabolic properties and immune functions of resident macrophages of the peritoneal cavity and splenic red pulp using high resolution quantitative proteomics

Background:Resident macrophages (Mϕs) are distributed throughout the body and are important for maintaining tissue homeostasis and for defence against infections. Tissue Mϕs are highly adapted to their microenvironment and thought to mediate tissue-specific functions involving metabolism and immune defence that are not fully elucidated. Methods:We have used high resolution quantitative proteomics to gain insights into the functions of two types of resident tissue Mϕs: peritoneal cavity Mϕs and splenic red pulp Mϕs.  The cellular expression levels of many proteins were validated by flow cytometry and were consistently in agreement with the proteomics data.Results:Peritoneal and splenic red pulp macrophages displayed major differences in cell surface phenotype reflecting their adaptation to different tissue microenvironments and tissue-specific functions. Peritoneal Mϕs were shown to be enriched in a number of key enzymes and metabolic pathways normally associated with the liver, such as metabolism of fructose, detoxification, nitrogen homeostasis and the urea cycle. Supporting these observations, we show that peritoneal Mϕs are able to utilise glutamine and glutamate which are rich in peritoneum for urea generation.  In comparison, splenic red pulp Mϕs were enriched in proteins important for adaptive immunity such as antigen presenting MHC molecules, in addition to proteins required for erythrocyte homeostasis and iron turnover. We also show that these tissue Mϕs may utilise carbon and nitrogen substrates for different metabolic fates to support distinct tissue-specific roles.Conclusions:This study provides new insights into the functions of tissue Mϕs in immunity and homeostasis.  The comprehensive proteomics data sets are a valuable resource for biologists and immunologists.

Immunological Activities of Crude Polysaccharides Extracts of Climacodon pulcherrimus (Phanerochaetaceae) in Lipopolysaccharide-Induced Rat Macrophages and Neutrophils' Responses

Mushroom contains a wide variety of components with high immune-modulating properties. Mushroom polysaccharides are known as immunocorrectors with wide areas of usage, which balance the immune system without resulting in the entire immune suppression or overreaction. To explore the potentially immunomodulatory role of Climacodon pulcherrimus, the present study was intended to evaluate the in vitro immunomodulatory activity of C. pulcherrimus polysaccharides (CPP) on rat neutrophils and macrophages. CPP was studied on lipopolysaccharide-induced neutrophils and macrophages' responses. The effect on phagocytosis, release of reactive oxygen intermediates (ROI), nitric oxide (NO), lysosomal enzyme release and neutrophil myeloperoxidase, and neutrophil adherence was assessed. The cytotoxicity of CPP against macrophages using 3-(4,5-dimethylthiazole-2-yl)-2, 5-diphenyltetrazolium bromide assay and neutral red inclusion assay was also assessed. ENPC (endopolysaccharides) markedly enhanced phagocytosis of macrophages and neutrophils, whereas the EXPC (exopolysaccharides) increased only that of neutrophils at 0.34 and 0.68 mg/mL. The production of NO evidently increased in ENPC- and EXPC-treated neutrophil and macrophage cultures. The production of ROI in a concentration-dependent manner increased in ENPC-treated (0.08-5.55 mg/mL) and EXPC-treated (0.17 and 0.34 mg/mL) macrophage cultures and ENPC-treated neutrophils, whereas it decreased in EXPC-treated neutrophils. The secretion of acid phosphatase increased in ENPC- and EXPC-treated macrophage and neutrophil cultures. Neutrophil myeloperoxidase release increased in EXPC-treated (5.55 mg/mL) cultures, whereas it decreased in ENPC-treated cultures. ENPC and EXPC increased the adhesion of neutrophils to microplate. These findings demonstrated that CPP displayed a dual mode of action, inhibiting or enhancing numerous phagocytic activities of macrophages and neutrophils.

Investigating coordination flexibility of glycerophosphodiesterase (GpdQ) through interactions with mono-, di-, and triphosphoester (NPP, BNPP, GPE, and paraoxon) substrates

Interactions of the catalytically active binuclear form of glycerophosphodiesterase (GpdQ) with chemically diverse substrates, i.e. phosphomono-, phosphodi-, and phosphotriester have been investigated using molecular dynamics (MD) simulations.

Design of smart targeted and responsive drug delivery systems with enhanced antibacterial properties

The use of antibiotics has been an epoch-making invention in the past few decades for the treatment of infectious diseases. However, the intravenous injection of antibiotics lacking responsiveness and targeting properties has led to low drug utilization and high cytotoxicity. More importantly, it has also caused the development and spread of drug-resistant bacteria due to repeated medication and increased dosage. The differences in the microenvironments of the bacterial infection sites and normal tissues, such as lower pH, high expression of some special enzymes, hydrogen peroxide and released toxins, etc., are usually used for targeted and controlled drug delivery. In addition, bacterial surface charges, antigens and the surface structures of bacterial cell walls are all different from normal tissue cells. Based on the special bacterial infection microenvironments and bacteria surface properties, a series of drug delivery systems has been constructed for highly efficient drug release. This review summarizes the recent progress in targeted and responsive drug delivery systems for enhanced antibacterial properties.

Oxidative stress and macrophages: driving forces behind exacerbations of asthma and chronic obstructive pulmonary disease?

Oxidative stress is a common feature of obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD). Lung macrophages are key innate immune cells that can generate oxidants and are known to display aberrant polarization patterns and defective phagocytic responses in these diseases. Whether these characteristics are linked in one way or another and whether they contribute to the onset and severity of exacerbations in asthma and COPD remain poorly understood. Insight into oxidative stress, macrophages, and their interactions may be important in fully understanding acute worsening of lung disease. This review therefore highlights the current state of the art regarding the role of oxidative stress and macrophages in exacerbations of asthma and COPD. It shows that oxidative stress can attenuate macrophage function, which may result in impaired responses toward exacerbating triggers and may contribute to exaggerated inflammation in the airways.

Diethylalkylsulfonamido(4-methoxyphenyl)methyl)phosphonate/phosphonic acid derivatives act as acid phosphatase inhibitors: synthesis accompanied by experimental and molecular modeling assessments

Purple acid phosphatases (PAPs) are binuclear metallo-hydrolases that have been isolated from various mammals, plants, fungi and bacteria. In mammals, PAP activity is associated with bone resorption and can lead to bone metabolic disorders such as osteoporosis; thus human PAP is an attractive target to develop anti-osteoporotic drugs. The aim of the present study was to investigate inhibitory effect of synthesized diethylalkylsulfonamido(4-methoxyphenyl)methyl)phosphonate/phosphonic acid derivatives as potential red kidney bean PAP (rkbPAP) inhibitors accompanied by experimental and molecular modeling assessments. Enzyme kinetic data showed that they are good rkbPAP inhibitors whose potencies improve with increasing alkyl chain length. Hexadecyl derivatives, as most potent compounds (Ki = 1.1 µM), inhibit rkbPAP in the mixed manner, while dodecyl derivatives act as efficient noncompetitive inhibitor. Also, analysis by molecular modeling of the structure of the rkbPAP-inhibitor complexes reveals factors, which may be important for the determination of inhibition specificity.

A Potent Tartrate Resistant Acid Phosphatase Inhibitor to Study the Function of TRAP in Alveolar Macrophages

The enzyme tartrate resistant acid phosphatase (TRAP, two isoforms 5a and 5b) is highly expressed in alveolar macrophages, but its function there is unclear and potent selective inhibitors of TRAP are required to assess functional aspects of the protein. We found higher TRAP activity/expression in lungs of patients with chronic obstructive pulmonary disease (COPD) and asthma compared to controls and more TRAP activity in lungs of mice with experimental COPD or asthma. Stimuli related to asthma and/or COPD were tested for their capacity to induce TRAP. Receptor activator of NF-κb ligand (RANKL) and Xanthine/Xanthine Oxidase induced TRAP mRNA expression in mouse macrophages, but only RANKL also induced TRAP activity in mouse lung slices. Several Au(III) coordination compounds were tested for their ability to inhibit TRAP activity and [Au(4,4′-dimethoxy-2,2′-bipyridine)Cl₂][PF₆] (AubipyOMe) was found to be the most potent inhibitor of TRAP5a and 5b activity reported to date (IC50 1.3 and 1.8 μM respectively). AubipyOMe also inhibited TRAP activity in murine macrophage and human lung tissue extracts. In a functional assay with physiological TRAP substrate osteopontin, AubipyOMe inhibited mouse macrophage migration over osteopontin-coated membranes. In conclusion, higher TRAP expression/activity are associated with COPD and asthma and TRAP is involved in regulating macrophage migration.

Effect of dietary arginine on the immune response and gene expression in head kidney and spleen following infection of Jian carp with Aeromonas hydrophila

This study was conducted to test the hypothesis that elevated dietary arginine enhances immunity of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed graded levels of dietary arginine for 9 weeks. Subsequently, a challenge test was conducted by injection of Aeromonas hydrophila. Head kidney and spleen weights, as well as erythrocyte and leukocyte counts were significantly influenced by dietary arginine levels. A similar trend was also observed for hemagglutination titre, serum lysozyme activity, IgM concentration, C3 and C4 content. The highest survival rates following A. hydrophila infection were obtained in fish fed the diets containing arginine at 16.1-21.9 g/kg diet. Phagocytic activity of leukocytes was significantly enhanced by dietary arginine supplementation. In contrast, acid phosphatase activity significantly decreased with dietary arginine levels. Dietary arginine levels did not have a significant effect on the total iron-binding capacity. Gene expression of TNF-α and TGF-β in head kidney significantly increased with dietary arginine levels up to 21.9 g/kg diet, and decreased thereafter. Fish fed the basal diet exhibited the highest IL-10 mRNA expression level. Gene expression of IL-1β and TOR increased with dietary arginine addition, reaching a plateau at 18.5 and 21.9 g arginine/kg diet, respectively. In spleen, higher IL-1β and TNF-α gene expressions were obtained in fish fed the diets containing 24.5 g arginine/kg diet than in fish fed the other dietary treatments. TGF-β mRNA expression levels were significantly lower in fish fed the diets containing ≤21.9 g arginine/kg diet. IL-10 and TOR mRNA expression levels were lower in fish fed 16.1 g arginine/kg diet, while 4E-BP mRNA expression levels increased with dietary arginine levels up to 12.7 g/kg diet and decreased thereafter. Our results indicate that arginine has beneficial effects on regulating mRNA expression of inflammatory cytokines, as well as TOR and 4E-BP and improving humoral and cellular immunity, therefore enhancing disease resistance of fish.

Effect of butyrate on immune response of a chicken macrophage cell line

Butyric acid is a major short chain fatty acid (SCFA), produced in the gastrointestinal tract by anaerobic bacterial fermentation, that has beneficial health effects in many species including poultry. To understand the immunomodulating effects of butyrate on avian macrophage, we treated a naturally transformed line of chicken macrophage cells named HTC with Na-butyrate in the absence or presence of Salmonella typhimurium lipopolysaccharide (LPS) or phorbol-12-myristate-13-acetate (PMA), a metabolic activator, evaluating its various functional parameters. The results demonstrate that, butyrate by itself had no significant effect on variables such as nitric oxide (NO) production and the expression of genes associated with various inflammatory cytokines but it inhibited NO production, and reduced the expression of cytokines such as IL-1β, IL-6, IFN-γ, and IL-10 in LPS-stimulated cells. Butyrate decreased the expression of TGF-β3 in the presence or absence of LPS, while it had no effect on IL-4, Tβ4, and MMP2 gene expression. In addition, butyrate augmented PMA induced oxidative burst indicated by DCF-DA oxidation and restored LPS induced attenuation of tartrate resistant acid phosphatase (TRAP) activity. Although butyrate had no significant effect on phagocytosis or matrix metalloproteinase (MMP) activities of resting macrophages, it significantly suppressed the effects induced by their respective stimulants such as LPS induced phagocytosis and PMA induced MMP expression. These results suggest that butyrate has immunomodulatory property in the presence of agents that incite the cells thus, has potential to control inflammation and restore immune homeostasis.

Extracellular ATP decreases trophoblast invasion, spiral artery remodeling and immune cells in the mesometrial triangle in pregnant rats

INTRODUCTION

Preeclampsia is characterized by deficient trophoblast invasion and spiral artery remodeling, a process governed by inflammatory cells. High levels of the danger signal extracellular adenosine triphosphate (ATP) have been found in women with preeclampsia and infusion of ATP in pregnant rats induced preeclampsia-like symptoms such as albuminuria and placental ischemia. We hypothesized that ATP inhibits trophoblast invasion and spiral artery remodeling and affects macrophages and natural killer (NK) cells present in the rat mesometrial triangle.

METHODS

Pregnant rats were infused with ATP or saline (control) on day 14 of pregnancy. Rats were sacrificed on day 15, 17 or 20 of pregnancy and placentas with mesometrial triangle were collected. Sections were stained for trophoblast cells, α-smooth muscle actin (spiral artery remodeling), NK cells and various macrophage populations. Expression of various cytokines in the mesometrial triangle was analyzed using real-time RT-PCR.

RESULTS

ATP infusion decreased interstitial trophoblast invasion on day 17 and spiral artery remodeling on day 17 and 20, increased activated tartrate resistant acid phosphatase (TRAP)-positive macrophages on day 15, decreased NK cells on day 17 and 20, and decreased inducible nitric oxide synthase (iNOS)-positive and CD206-positive macrophages and TNF-α and IL-33 expression at the end of pregnancy (day 20).

DISCUSSION

Interstitial trophoblast invasion and spiral artery remodeling in the rat mesometrial triangle were decreased by infusion of ATP. These ATP-induced modifications were preceded by an increase in activated TRAP-positive macrophages and coincided with NK cell numbers, suggesting that they are involved.

CONCLUSION

Trophoblast invasion and spiral artery remodeling may be inhibited by ATP-induced activated macrophages and decreased NK cells in the mesometrial triangle in rat pregnancy.

Caveolae-mediated endocytosis of the glucosaminoglycan-interacting adipokine tartrate resistant acid phosphatase 5a in adipocyte progenitor lineage cells

Adipogenesis depends on growth factors controlling proliferation/differentiation of mesenchymal stem cells (MSCs). Membrane binding and endocytosis of growth factors are often coupled to receptor activation and downstream signaling leading to specific cellular responses. The novel adipokine tartrate-resistant acid phosphatase (TRAP) 5a exhibits a growth factor-like effect on MSCs and pre-adipocytes and induces hyperplastic obesity in vivo. However its molecular interaction with pre-adipocytes remains unknown. Therefore, this study aimed to investigate membrane interaction of TRAP and its endocytosis routes in pre-adipocytes. Confocal and/or electron microscopy were used to detect TRAP in untreated or TRAP 5a/b treated pre-adipocytes under conditions that allow or inhibit endocytosis in combination with co-staining of endocytotic vesicles. TRAP interaction with heparin/heparan sulfate was verified by gel filtration. It could be shown that TRAP 5a, but not 5b, binds to the membrane of pre-adipocytes where it co-localizes with heparin-sulfate proteoglycan glypican-4. Also in vitro, TRAP 5a exhibited affinity for both heparin and heparan sulfate with heparin inhibiting its enzyme activity. Upon caveolae-mediated endocytosis of saturating levels of TRAP 5a, TRAP 5a co-localized intracellularly with glypican-4 and late endosomal marker Rab-7 positive vesicles. The protein was also located in multivesicular bodies (MVBs) but did not co-localize with lysosomal marker LAMP-1. TRAP 5a endocytosis was also detectable in pre-osteoblasts, but not fibroblasts, embryonic MSCs or mature adipocytes. These results indicate that TRAP 5a exhibits binding to cell surface, endocytosis and affinity to glucosaminoglycans (GAGs) in pre-adipocyte and pre-osteoblast lineage cells in a manner similar to other heparin-binding growth factors.

Macrophage expression of tartrate-resistant acid phosphatase as a prognostic indicator in colon cancer

Recent research has indicated that separate populations of macrophages are associated with differing outcomes in cancer survival. In our study, we examine macrophage expression of tartrate-resistant acid phosphatase (TRAP) and its effect on survival in colon cancer. Immunohistochemical analysis on colorectal adenocarcinomas confirmed macrophage expression of TRAP. Co-localization of TRAP with CD68, a pan-macrophage marker, revealed that TRAP is present in some but not all sub-populations of macrophages. Further co-localization of TRAP with CD163, an M2 marker, revealed that TRAP is expressed by both M2 and non-M2 macrophages. TRAP expression was then measured using the AQUA method of quantitative immunofluorescence in a tissue microarray consisting of 233 colorectal cancer patients seen at Yale-New Haven Hospital. Survival analysis revealed that patients with high TRAP expression have a 22 % increase in 5-year survival (uncorrected log-rank p = 0.025) and a 47 % risk reduction in disease-specific death (p = 0.02). This finding was validated in a second cohort of older cases consisting of 505 colorectal cancer patients. Patients with high TRAP expression in the validation set had a 19 % increase in 5-year survival (log-rank p = 0.0041) and a 52 % risk reduction in death (p = 0.0019). These results provide evidence that macrophage expression of TRAP is associated with improved outcome and implicates TRAP as a potential biomarker in colon cancer.

Effects of temperature acclimation on Pacific bluefin tuna (Thunnus orientalis) cardiac transcriptome

Little is known about the mechanisms underpinning thermal plasticity of vertebrate hearts. Bluefin tuna hearts offer a unique model to investigate processes underlying thermal acclimation. Their hearts, while supporting an endothermic physiology, operate at ambient temperature, and are presented with a thermal challenge when migrating to different thermal regimes. Here, we examined the molecular responses in atrial and ventricular tissues of Pacific bluefin tuna acclimated to 14°C, 20°C, and 25°C. Quantitative PCR studies showed an increase in sarcoplasmic reticulum Ca2+ ATPase gene expression with cold acclimation and an induction of Na+/Ca2+-exchanger gene at both cold and warm temperatures. These data provide evidence for thermal plasticity of excitation-contraction coupling gene expression in bluefin tunas and indicate an increased capacity for internal Ca2+ storage in cardiac myocytes at 14°C. Transcriptomic analysis showed profound changes in cardiac tissues with acclimation. A principal component analysis revealed that temperature effect was greatest on gene expression in warm-acclimated atrium. Overall data showed an increase in cardiac energy metabolism at 14°C, potentially compensating for cold temperature to optimize bluefin tuna performance in colder oceans. In contrast, metabolic enzyme activity and gene expression data suggest a decrease in ATP production at 25°C. Expression of genes involved in protein turnover and molecular chaperones was also decreased at 25°C. Expression of genes involved in oxidative stress response and programmed cell death suggest an increase in oxidative damage and apoptosis at 25°C, particularly in the atrium. These findings provide insights into molecular processes that may characterize cardiac phenotypes at upper thermal limits of teleosts.

Bacteria-responsive multifunctional nanogel for targeted antibiotic delivery

Bacteria-Responsive Multifunctional Nanogel: We developed a bacteria-responsive multifunctional nanogel for targeted antibiotic delivery, in which bacterial enzymes are utilized to trigger antibiotic release by degrading the polyphosphoester core. The mannosylated nanogel preferentially delivers drugs to macrophages and leads to drug accumulation at bacterial infection sites through macrophage transport. This nanogel provides macrophage targeting and lesion site-activatable drug release properties, which enhances bacterial growth inhibition.

Binuclear metallohydrolases: complex mechanistic strategies for a simple chemical reaction

Binuclear metallohydrolases are a large family of enzymes that require two closely spaced transition metal ions to carry out a plethora of hydrolytic reactions. Representatives include purple acid phosphatases (PAPs), enzymes that play a role in bone metabolism and are the only member of this family with a heterovalent binuclear center in the active form (Fe(3+)-M(2+), M = Fe, Zn, Mn). Other members of this family are urease, which contains a di-Ni(2+) center and catalyzes the breakdown of urea, arginase, which contains a di-Mn(2+) center and catalyzes the final step in the urea cycle, and the metallo-β-lactamases, which contain a di-Zn(2+) center and are virulence factors contributing to the spread of antibiotic-resistant pathogens. Binuclear metallohydrolases catalyze numerous vital reactions and are potential targets of drugs against a wide variety of human disorders including osteoporosis, various cancers, antibiotic resistance, and erectile dysfunctions. These enzymes also tend to catalyze more than one reaction. An example is an organophosphate (OP)-degrading enzyme from Enterobacter aerogenes (GpdQ). Although GpdQ is part of a pathway that is used by bacteria to degrade glycerolphosphoesters, it hydrolyzes a variety of other phosphodiesters and displays low levels of activity against phosphomono- and triesters. Such a promiscuous nature may have assisted the apparent recent evolution of some binuclear metallohydrolases to deal with situations created by human intervention such as OP pesticides in the environment. OP pesticides were first used approximately 70 years ago, and therefore the enzymes that bacteria use to degrade them must have evolved very quickly on the evolutionary time scale. The promiscuous nature of enzymes such as GpdQ makes them ideal candidates for the application of directed evolution to produce new enzymes that can be used in bioremediation and against chemical warfare. In this Account, we review the mechanisms employed by binuclear metallohydrolases and use PAP, the OP-degrading enzyme from Agrobacterium radiobacter (OPDA), and GpdQ as representative systems because they illustrate both the diversity and similarity of the reactions catalyzed by this family of enzymes. The majority of binuclear metallohydrolases utilize metal ion-activated water molecules as nucleophiles to initiate hydrolysis, while some, such as alkaline phosphatase, employ an intrinsic polar amino acid. Here we only focus on catalytic strategies applied by the former group.

A molecular description of acid phosphatase

Acid phosphatase is ubiquitous in distribution in various organisms. Although it catalyzes simple hydrolytic reactions, it is considered as an interesting enzyme in biological systems due to its involvement in different physiological activities. However, earlier reviews on acid phosphatase reveal some fragmentary information and do not give a holistic view on this enzyme. So, the present review summarizes studies on biochemical properties, structure, catalytic mechanism, and applications of acid phosphatase. Recent advancement of acid phosphatase in agricultural and clinical fields is emphasized where it is presented as potent agent for sustainable agricultural practices and diagnostic marker in bone metabolic disorders. Also, its significance in prostate cancer therapies as a therapeutic target has been discussed. At the end, current studies and prospects of immobilized acid phosphatase are included.

Characterization of acid phosphatase from the tick Haemaphysalis longicornis

The full-length cDNA encoding acid phosphatase (HL-3) from Haemaphysalis longicornis was obtained by 5' rapid amplification of cDNA ends (RACE). The cDNA contained a 1137 bp open reading frame (ORF) coding for 356 amino acids with a predicted theoretical isoelectric point (pI) of 6.35 and molecular weight of 41.0 kDa. The recombinant protein was expressed in Escherichia coli. The enzyme could hydrolyze para-nitrophenyl phosphate (pNPP) substrate at an optimum pH of 5.0. Real-time RT-PCR analysis showed that the HL-3 transcripts were expressed in various stages of unfed ticks and were significantly induced by blood feeding. Furthermore, the expression of HL-3 in midguts was significantly higher than in other tested tissues of partially fed adult ticks. The transcripts of the HL-3 mRNA in lipopolysaccharide (LPS)-injected ticks were 1.75 times of the PBS-injected control; Theileria sergenti infected larvae expressed 3.86 more times than that of uninfected ones. Western blot analysis showed that rabbit antiserum against the recombinant rHL-3 could recognize a native protein of approximately 41.0 kDa in the lysates from different stages of ticks. Vaccination of rabbits with the rHL-3 conferred partial protective immunity against ticks, resulting in 28% mortality and 10.6% reduction in engorgement weight of adult ticks, respectively. These results suggested that the HL-3 was involved in tick innate immunity and could be used as a potential candidate antigen for the development of anti-tick vaccines.

Bisphosphonates in phenytoin-induced bone disorder

Chronic administration of phenytoin (PHT) has been associated with bone loss. Bisphosphonates [alendronate (ALD), ibandronate (IBD) and risedronate (RSD)] are potential candidates to prevent PHT-induced bone disorders, and the present study evaluated their effect on the antiepileptic efficacy of PHT. The PHT-induced depletion in folic acid (FA), vitamin B6 and vitamin B12 results in hyperhomocysteinemia. The elevated circulating homocysteine (hcy) could be a risk indicator for micronutrient-deficiency-related osteoporosis via generation of free radicals. Thus, an attempt was also made to unravel the PHT's and bisphosphonates' effect on hcy. Male mice received PHT (35 mg/kg, p.o.) for 90 days to induce bone loss. ALD, RSD and IBD were administered orally at doses 0.65 mg/kg, 0.33 mg/kg, and 0.17 mg/kg respectively, for prevention and 1.3mg/kg, 0.65 mg/kg, and 0.33 mg/kg respectively, for treatment of PHT-induced bone loss. The bone loss was confirmed by bone mineral density (BMD) analysis and bone turnover markers. Serum levels of hcy and FA were estimated along with hydrogen peroxide levels and total antioxidant capacity in order to assess the antioxidant profile of bisphosphonates. The induction of bone loss by PHT was marked by lowered BMD and altered bone turnovers. ALD and RSD administration to PHT treated groups significantly reverted the bony adverse effects. No such effects were observed with IBD. In the bisphosphonates treated groups, hcy levels were statistically at par with the control group. PHT at 35 mg/kg, p.o. could compromise bone mass and thus, could be a model of bone demineralization in mice. The ALD, IBD and RSD have no pharmacodynamic interaction when administered along with PHT at the experimental level. Thus, their usage in the management of PHT-induced bone disease could be worthwhile if clinically approved.

Biology and clinical significance of tartrate-resistant acid phosphatases: new perspectives on an old enzyme

Type 5 tartrate-resistant acid phosphatase (TRAP) has been a clinically relevant biomarker for about 50 years. It has always been a reliable and specific cytochemical marker for hairy cell leukemia and for differentiated cells of monocytic lineage. Only recently has the test for serum TRAP activity been accepted as sensitive and specific enough for clinical use as a marker of osteoclasts and bone resorption. This has come about through steady advances in knowledge about TRAP enzymology, structure, function, and molecular regulation and a consequent appreciation that TRAP isoforms 5a and 5b have very different clinical significance. As a measure of osteoclast number and bone resorption, TRAP 5b has diagnostic and prognostic applications in osteoporosis, cancers with bone metastasis, chronic renal failure, and perhaps other metabolic and pathologic bone diseases. Serum TRAP 5a, on the other hand, has no relationship to bone metabolism but seems instead to be a measure of activated macrophages and chronic inflammation. Exploration of the real clinical usefulness of serum TRAP 5a for diagnosis and disease management in a wide variety of chronic inflammatory diseases is only now beginning. This perspective traces the important basic scientific developments that have led up to the refinement of serum TRAP isoform immunoassays and their validation as biomarkers of disease. Many unanswered questions remain, providing a wealth of opportunity for continued research of this multifaceted enzyme.

Induction and cellular expression of tartrate resistant acid phosphatase during dextran sodium sulphate induced colitis in rats

The aim of this study was to investigate the cellular and molecular expression of tartrate resistant acid phosphatase (TRAP) as a marker of activated macrophages in macrophage dependent dextran sulphate sodium (DSS)-induced colitis in rats. In normal colon, TRAP+/CX(3)CR(1)+ macrophages were located in the upper part of the lamina propria. In the early stage (day 1-3) of acute colitis prior to histopathological changes, induction of the cytokines TNFalpha, IL-12 and IFN gamma occurred concomitant with increased mRNA and enzyme activity of TRAP along with a slight increase of TRAP immunolabelling in macrophages of the upper lamina propria, suggesting induction of TRAP in resident macrophages. Among these cytokines, TNFalpha up-regulated TRAP expression in the RAW 264.7 monocyte/macrophage cell line. In a later phase (day 7) with fulminant colitis, a massive infiltration of macrophages including recruited TRAP+/CCR2+ cells was observed also in the lower part of the lamina propria as well as in the submuscular layer. Additionally, differentiated cellular expression of pro- and mature TRAP also suggest that mucosal macrophages in the lower part of lamina propria bordering the sub-mucosa provide a source of replenishment of macrophages situated in the upper lamina propria. In conclusion, induction of TRAP provides an early sign of macrophage responsiveness in DSS induced colitis.

Role of NADPH oxidase in formation and function of multinucleated giant cells

Macrophages play essential roles in a wide variety of physiological and pathological processes. One of the unique features of these phagocytic leukocytes is their ability to fuse, forming multinucleated giant cells. Multinucleated giant cells are important mediators of tissue remodeling and repair and are also responsible for removal or sequestration of foreign material, intracellular bacteria and non-phagocytosable pathogens, such as parasites and fungi. Depending on the tissue where fusion occurs and the inflammatory insult, multinucleated giant cells assume distinctly different phenotypes. Nevertheless, the ultimate outcome is the formation of large cells that can resorb bone tissue (osteoclasts) or foreign material and pathogens (giant cells) extracellularly. While progress has been made in recent years, the mechanisms and factors involved in macrophage fusion are still not fully understood. In addition to cytokines and a number of adhesion proteins and receptors, it is becoming increasingly clear that NADPH oxidase-generated reactive oxygen species (ROS) also play an important role in macrophage fusion. In this review, we provide an overview of macrophage multinucleation, with a specific focus on the role of NADPH oxidases and ROS in macrophage fusion and in the function of multinucleated giant cells. In addition, we provide an updated overview of the role of these cells in inflammation and various autoimmune diseases.

Gene expression signature for spontaneous cancer regression in melanoma pigs

Incomplete spontaneous regression of melanoma is common. However, complete melanoma regression is still a very rare phenomenon. Because melanoma is the most immunogenic human malignancy, the mechanisms leading to regression, based on accumulative evidence, are the host's immune responses. Unfortunately, therapies aiming to enhance the patient's natural immunity against melanoma have yet to meet their expectations. Reasons for failure include various immune escape mechanisms, induced by the tumor, that subsequently lead to tolerance. Here, we performed time-dependent gene expression profiling to unravel molecular changes involved in the transition of progressive melanoma to complete tumor regression using a porcine model. The melanoblastomabearing Libechov minipigs are highly suitable for this study because these animals exhibit naturally occurring and regressing melanomas. We were able to identify a molecular signature of the melanoma regression process. Genes regulated in this signature were associated with 1) cell cycle, 2) immune response, and 3) melanocyte differentiation. These genes may shed light on molecular mechanisms involved in complete melanoma regression and indicate what improvements are needed for successful antimelanoma therapy.

Immunolocalisation of the uterine secretory proteins uterocalin, uteroferrin and uteroglobin in the mare's uterus and placenta throughout pregnancy

Previous studies have shown that the equine uterus produces many progesterone-dependent proteins throughout gestation. In particular, uterocalin and uteroferrin are detectable using electrophoresis or blot analyses but information regarding the immunohistochemical placental distribution of these two proteins is rare and information regarding uteroglobin is still lacking. The aim of the present study was to co-immunolocalise these three secretory proteins in the mare's uterus throughout gestation in an effort to understand their functional role in the maintenance of pregnancy. Therefore, endometrial biopsy samples were obtained from 20 pregnant mares between 16 and 309 days of gestation and labelled immunohistochemically for uteroglobin, uteroferrin and uterocalin. Uteroferrin remained detectable in almost every endometrial gland at all stages but with an increase in staining intensity as gestation advanced. The most progesterone-dependent protein, uterocalin, showed variable staining throughout gestation with the most intense labelling in early pregnancy and during the period of endometrial cup reaction. Uteroglobin secretion was only detectable in traces and only in individual glands throughout gestation. The results indicate that uterocalin and uteroferrin, but not uteroglobin, may play important roles in supplying nutrients for the conceptus, thereby contributing to the maintenance of pregnancy. However, further investigations are necessary to understand the role of uteroglobin during gestation.

Tartrate-resistant acid phosphatase (TRAP) and the osteoclast/immune cell dichotomy

Tartrate-resistant acid phosphatase (TRAP), once considered to be just a histochemical marker of osteoclasts is now recognised to be a molecule of widespread occurrence with functions in both the skeleton and the immune system. TRAP is expressed by osteoclasts, macrophages, dendritic cells and a number of other cell types. It has a critical role in many biological processes including skeletal development, collagen synthesis and degradation, the mineralisation of bone, cytokine production by macrophages and dendritic cells, macrophage recruitment, dendritic cell maturation and a role in the development of Th1 responses. TRAP is able to degrade skeletal phosphoproteins including osteopontin (OPN), identical to the T-cell cytokine, Eta-1. In this review, we discuss the role of TRAP in bone and immune cells and suggest that TRAP may be implicated in autoimmune disorders regulated by Th1 inflammatory responses as well as certain cancers.

The zebrafish genome in context: ohnologs gone missing

Some zebrafish genes appear to lack an ortholog in the human genome and researchers often call them "novel" genes. The origin of many so-called "novel" genes becomes apparent when considered in the context of genome duplication events that occurred during evolution of the phylum Chordata, including two rounds at about the origin of the subphylum Vertebrata (R1 and R2) and one round before the teleost radiation (R3). Ohnologs are paralogs stemming from such genome duplication events, and some zebrafish genes said to be "novel" are more appropriately interpreted as "ohnologs gone missing", cases in which ohnologs are preserved differentially in different evolutionary lineages. Here we consider ohnologs present in the zebrafish genome but absent from the human genome. Reasonable hypotheses are that lineage-specific loss of ohnologs can play a role in establishing lineage divergence and in the origin of developmental innovations. How does the evolution of ohnologs differ from the evolution of gene duplicates arising from other mechanisms, such as tandem duplication or retrotransposition? To what extent do different major vertebrate lineages or different teleost lineages differ in ohnolog content? What roles do differences in ohnolog content play in the origin of developmental mechanisms that differ among lineages? This review explores these questions.

Effect of starvation on global gene expression and proteolysis in rainbow trout (Oncorhynchus mykiss)

Background

Fast, efficiently growing animals have increased protein synthesis and/or reduced protein degradation relative to slow, inefficiently growing animals. Consequently, minimizing the energetic cost of protein turnover is a strategic goal for enhancing animal growth. Characterization of gene expression profiles associated with protein turnover would allow us to identify genes that could potentially be used as molecular biomarkers to select for germplasm with improved protein accretion.

Results

We evaluated changes in hepatic global gene expression in response to 3-week starvation in rainbow trout (Oncorhynchus mykiss). Microarray analysis revealed a coordinated, down-regulated expression of protein biosynthesis genes in starved fish. In addition, the expression of genes involved in lipid metabolism/transport, aerobic respiration, blood functions and immune response were decreased in response to starvation. However, the microarray approach did not show a significant increase of gene expression in protein catabolic pathways. Further studies, using real-time PCR and enzyme activity assays, were performed to investigate the expression of genes involved in the major proteolytic pathways including calpains, the multi-catalytic proteasome and cathepsins. Starvation reduced mRNA expression of the calpain inhibitor, calpastatin long isoform (CAST-L), with a subsequent increase in the calpain catalytic activity. In addition, starvation caused a slight but significant increase in 20S proteasome activity without affecting mRNA levels of the proteasome genes. Neither the mRNA levels nor the activities of cathepsin D and L were affected by starvation.

Conclusion

These results suggest a significant role of calpain and 20S proteasome pathways in protein mobilization as a source of energy during fasting and a potential association of the CAST-L gene with fish protein accretion.

Sequence and TLR9 independent increase of TRACP expression by antisense DNA and siRNA molecules

Reactive oxygen species generating activity of tartrate-resistant acid phosphatase (TRACP) has been suggested to have several functions in TRACP expressing bone resorbing osteoclasts, macrophages, and dendritic cells. This work aimed to study the TRACP knock down phenotype in osteoclasts by using antisense DNA and RNA interference methods. Unexpectedly, both TRACP specific DNA oligonucleotides and siRNA molecules extensively increased the TRACP expression in human osteoclasts and monocytes. Toll-like receptor 9 (TLR9) is an immunity sensor for CpG motifs in DNA. We cultured bone marrow-derived osteoclast precursor cells from wild-type and TLR9-/- mice with CpG and non-CpG DNA oligonucleotides, and observed that the increased TRACP expression was sequence and TLR9 independent. In contrast, cells with increased TRACP activity showed decreased activity of tartrate-sensitive acid phosphatases.

CONCLUSION

DNA oligonucleotides and RNA molecules extensively increase TRACP expression in monocyte-macrophage lineage. These results suggest a potential role of TRACP in pathogen recognition and in innate immunity.

RNA interference tolerates 2'-fluoro modifications at the Argonaute2 cleavage site

Short interfering RNA (siRNA) molecules with good gene-silencing properties are needed for drug development based on RNA interference (RNAi). An initial step in RNAi is the activation of the RNA-induced silencing complex RISC, which requires degradation of the sense strand of the siRNA duplex. Although various chemical modifications have been introduced to the antisense strand, modifications to the Argonaute2 (Ago2) cleavage site in the sense strand have, so far, not been described in detail. In this work, novel 2'-F-purine modifications were introduced to siRNAs, and their biological efficacies were tested in cells stably expressing human tartrate-resistant acid phosphatase (TRACP). A validated siRNA that contains both purine and pyrimidine nucleotides at the putative Ago2 cleavage site was chemically modified to contain all possible combinations of 2'-fluorinated 2'-deoxypurines and/or 2'-deoxypyrimidines in the antisense and/or sense strands. The capacity of 2'-F-modified siRNAs to knock down their target mRNA and protein was studied, together with monitoring siRNA toxicity. All 2'-F-modified siRNAs resulted in target knockdown at nanomolar concentrations, despite their high thermal stability. These experiments provide the first evidence that RISC activation not only allows 2'-F modifications at the sense-strand cleavage site, but also increase the biological efficacy of modified siRNAs in vitro.

Altered collagen in tartrate-resistant acid phosphatase (TRAP)-deficient mice: a role for TRAP in bone collagen metabolism

Tartrate-resistant acid phosphatase (TRAP) is an iron-containing protein that is highly expressed by osteoclasts, macrophages, and dendritic cells. The enzyme is secreted by osteoclasts during bone resorption, and serum TRAP activity correlates with resorptive activity in disorders of bone metabolism. TRAP is essential for normal skeletal development. In knockout mice lacking TRAP, bone shape and modeling is altered with increased mineral density. Here, we report the effect of TRAP on the biochemical and biomechanical properties of collagen, the major protein constituting the bone matrix, using these mice. Femurs from TRAP-/- and wild-type mice were used in these studies. The biomechanical properties were investigated using a three-point bending technique. Collagen synthesis was determined by measuring cross-link content using high-performance liquid chromatography and amino acid analysis. Collagen degradation was determined by measuring matrix metalloproteinase-2 (MMP-2) activity. The rates of collagen synthesis and degradation were significantly greater in bones from TRAP-/- mice compared with wild type. At 8 weeks, there was an increase in the intermediate cross-links but no significant difference in animals aged 6 months. There was a significant increase in mature cross-links at both ages. A significant increase in MMP-2 production both pro and active was observed. A significant increase in ultimate stress and Young's modulus of elasticity was needed to fracture the bones from mice deficient in TRAP. We conclude that both synthesis as well as degradation of collagen are increased when TRAP is absent in mice at 8 weeks and 6 months of age, showing that TRAP has an important role in the metabolism of collagen.

Immuno-stimulating properties of diosgenyl saponins isolated from Paris polyphylla

The effects of three diosgenyl saponins isolated from Paris polyphylla on the immuno-stimulating activity in relation to phagocytosis, respiratory burst, and nitric oxide production in mouse macrophage cells RAW 264.7 have been investigated. Our results showed that all three diosgenyl saponins significantly enhanced phagocytic activity that increased with the concentration of saponins to reach a maximum, and then tended to decrease with higher concentrations. Saponins with sugar moiety directly induced respiratory burst response in RAW 264.7 cells that increased with the concentrations and reached a maximum, then decreased with higher concentrations after 2-h incubations, however, diosgenin had no PMA-triggered respiratory burst response. Treatment of RAW 264.7 cells with saponins with sugar moiety for 24-h caused a significant increase in the production of nitric oxide, while diosgenin had no effect at all. Consequently, relationship between molecular structures of three diosgenyl saponins and their immunomodulatory activities was discussed, and a possible mechanism of immuno-stimulating function of diosgenyl saponins was accordingly explored.

Expression and proteolytic processing of mammalian purple acid phosphatase in CHO-K1 cells

Rat recombinant purple acid phosphatase (PAP) stably expressed in fibroblast-like CHO-K1 cells was purified and characterized with respect to post-translational modifications such as N-glycosylation and proteolytic processing in order to elucidate subcellular and molecular pathways for proteolytic activation. In these cells, proteolytically processed PAP was more abundant than the monomeric form. PAP-transfected CHO-K1 cells were expressing active cathepsin K intracellularly, which was partially co-localized with PAP. However, neither cathepsin K nor trypsin digestion of the purified monomeric PAP in vitro did result in a two-subunit form with kinetic and electrophoretic properties resembling the endogenous cellular two-subunit form. Treatment of PAP-transfected CHO-K1 cells with the cysteine proteinase inhibitor E-64 suggested that only a minor fraction of secreted PAP is processed intracellularly by cysteine proteinases. These data do not support a dominant or critical role for cathepsins or trypsin-like serine proteinases in the proteolytic activation of PAP in CHO-K1 cells, implicating yet unidentified proteinases in the proteolytic processing of both intracellular and secreted PAP in this cell line.

The bacterial gene lfpA influences the potent induction of calcitonin receptor and osteoclast-related genes in Burkholderia pseudomallei-induced TRAP-positive multinucleated giant cells

Burkholderia pseudomallei is a facultative intracellular pathogen and the causative agent of melioidosis, a spectrum of potentially fatal diseases endemic in Northern Australia and South-East Asia. We demonstrate that B. pseudomallei rapidly modifies infected macrophage-like cells in a manner analagous to osteoclastogenesis. These alterations include multinucleation and the expression by infected cells of mRNA for factors required for osteoclastogenesis: the chemokines monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1 gamma (MIP-1gamma), 'regulated on activation normal T cell expressed and secreted' (RANTES) and the transcription factor 'nuclear factor of activated T-cells cytoplasmic 1' (NFATc1). An increase in expression of these factors was also observed after infection with Burkholderia thailandensis. Expression of genes for the osteoclast markers calcitonin receptor (CTR), cathepsin K (CTSK) and tartrate-resistant acid phosphatase (TRAP) was also increased by B. pseudomallei-infected, but not by B. thailandensis-infected cells. The expression by B. pseudomallei-infected cells of these chemokine and osteoclast marker genes was remarkably similar to cells treated with RANKL, a stimulator of osteoclastogenesis. Analysis of dentine resorption by B. pseudomallei-induced osteoclast-like cells revealed that demineralization may occur but that authentic excavation does not take place under the tested conditions. Furthermore, we identified and characterized lfpA (for lactonase family protein A) in B. pseudomallei, which shares significant sequence similarity with the eukaryotic protein 'regucalcin', also known as 'senescence marker protein-30' (SMP-30). LfpA orthologues are widespread in prokaryotes and are well conserved, but are phylogenetically distinct from eukaryotic regucalcin orthologues. We demonstrate that lfpA mRNA expression is dramatically increased in association with macrophage-like cells. Mutation of lfpA significantly reduced expression of the tested host genes, relative to the response to wild-type B. pseudomallei. We also show that lfpA is required for optimal virulence in vivo.

TRACP Influences Th1 pathways by affecting dendritic cell function

TRACP, a marker of osteoclasts, is also expressed by cells of the immune system. We identified a novel function for TRACP in the dendritic cell. DCs from TRACP knockout mice have impaired maturation and trigger reduced Th1 responses in vivo. We postulate that TRACP has an important role in the presentation of antigens to T cells.

INTRODUCTION

TRACP is highly expressed by osteoclasts, activated macrophages, and dendritic cells (DCs). Knockout mice lacking TRACP have an intrinsic defect in osteoclastic resorption and macrophages that display abnormal immunomodulatory responses and cytokine secretion profiles. Our aim in this study was to investigate the significance of TRACP in the inductive phase of the immune response by examining dendritic cells from TRACP(-/-) mice.

MATERIALS AND METHODS

Maturational state and function of leukocyte subsets in mice was assessed by flow cytometry. The ability of the immune system to respond to nonspecific activation and to specific antigen was assessed by delayed type hypersensitivity and the presence of isotype-specific serum antibody in vivo and T-cell proliferation and cytokine production in vitro.

RESULTS

The ability of lipopolysaccharide (LPS) to upregulate MHC II and CD80 in DCs from TRACP(-/-) mice was reduced compared with wildtype mice, although production of IL-10 by DCs from TRACP-deficient animals was increased. T- and B-cell responses not involving antigen presentation (anti-CD3, TNP-ficoll) were normal in TRACP(-/-) mice, but responses to T-dependent antigens were impaired. Specifically, TRACP(-/-) mice had defective delayed hypersensitivity responses to picryl chloride and reduced proliferative responses to ovalbumin compared with wildtype mice. In response to ovalbumin, but not anti-CD3, T cells from TRACP(-/-) mice produced less interferon-gamma (IFN-gamma), but there was no difference in IL-4 production: TRACP(-/-) mice also produced less ovalbumin (OVA)-specific IgG2a after immunization.

CONCLUSIONS

The finding that DCs from TRACP(-/-) mice have impaired maturation and defective Th1 responses shows that TRACP is important for polarizing responses in naïve T cells to antigen-presented dendritic cells.