Murine alpha-2-macroglobulin increase during inflammatory responses and tumor growth

Objective and Design: To determine the alpha-2-macroglobulin (alpha2M) levels in mice during acute and chronic inflammatory responses. Materials and Methods: Inflammation was induced by one of the following stimuli: carrageenin, zymosan, lipopolysacharide, thioglycollate, bacilli Calmette Guerin, PPD (in pre-immunized and non-immunized animals) and tumor cells. The concentration of alpha2M was determined in plasma or peritoneal liquid by electroimmunoassay. Results: In all the treatments employed, the plasma levels of alpha2M were higher than in untreated animals. This increase varied from 9%, 24 h after injection up a maximum of 66% 72 h post-injection. When compared to animals injected only with saline, the increases were significant 48 h after treatment with either zymosan or LPS, and 72 h after treatment with either thioglycollate or carrageenin. Treatment with BCG triggers an increase in alpha2M levels after 24 h (18.60%) and 48 h (27.90%). Immunized mice presented higher levels of this protein than non-immunized animals after challenge with PPD. The growth of Ehrlich tumor cells in the peritoneal cavity was directly correlated with the local levels of alpha2M which increased 3.5 fold, 10 days after injection. Conclusions: These results strongly indicate that in mice, the concentration of alpha2M can increase during acute and chronic inflammatory reactions with kinetics dependent on the particular kind of inflammatory agent.

The protease inhibitor alpha-2-macroglobulin-like-1 is the p170 antigen recognized by paraneoplastic pemphigus autoantibodies in human

Paraneoplastic pemphigus (PNP) is a devastating autoimmune blistering disease, involving mucocutaneous and internal organs, and associated with underlying neoplasms. PNP is characterized by the production of autoantibodies targeting proteins of the plakin and cadherin families involved in maintenance of cell architecture and tissue cohesion. Nevertheless, the identity of an antigen of Mr 170,000 (p170), thought to be critical in PNP pathogenesis, has remained unknown.

Anti-Alpha-2-Macroglobulin-Like-1 Autoantibodies Are Detected Frequently and May Be Pathogenic in Paraneoplastic Pemphigus

Paraneoplastic pemphigus (PNP) shows autoantibodies mainly to plakin and desmosomal cadherin family proteins. We have recently identified alpha-2-macroglobulin-like-1 (A2ML1), a broad range protease inhibitor, as a unique PNP antigen. In this study, we tested a large number of PNP sera by various methods. Forty (69.0%) of 58 PNP sera recognized A2ML1 recombinant protein expressed in COS7 cells by immunofluorescence (IF) and/or immunoprecipitation (IP)/immunoblotting (IB). IP/IB showed higher sensitivity than IF. In addition, 22 (37.9%) PNP sera reacted with A2ML1 by IB of cultured normal human keratinocytes (NHKs) under non-reducing conditions. Statistical analyses using various clinical and immunological data showed that the presence of anti-A2ML1 autoantibodies was associated with early disease onset and absence of ocular lesions. Next, to investigate the pathogenic role of anti-A2ML1 antibody, we performed additional functional studies. Addition of anti-A2ML1 polyclonal antibody to culture media decreased NHK cell adhesion examined by dissociation assay, and increased plasmin activity detected by casein zymography, suggesting that anti-A2ML1 antibody may decrease NHK cell adhesion through plasmin activation by inhibition of A2ML1. This study demonstrates that autoantibodies to A2ML1 are frequently and specifically detected and may have a pathogenic role in PNP.

Structural studies of proteinase entrapment by human alpha 2-macroglobulin using 3-D electron microscopy

Human a2 -macroglobulin ( a2 M; homotetramer, Mr 720 kDa) is an essential scavenger of proteinases in the serum. Each of its four subunits has a ‘bait region’, with cleavage sequences for almost all endo-proteinases, an unusual thiol ester moiety and a receptor-binding domain (RBD). Bait region cleavage in native a2 M ( a2 M-N) by a proteinase results in rapid thiol ester breakage, with a large-scale structural transformation, in which a2 M uniquely entraps the proteinase in a cage-like structure and exposes receptor-binding domains for rapid endocytosis. Transformed a2 M ( a2 M-TR) contains up to two proteinases, which remain active to small substrates. 3-D electron microscopy is optimally suited to study this unusual structural change at resolutions near (1/30) Å−1. ^ The structural importance of the thiol esters was demonstrated by a genetically-engineered a2 M, with the cysteines involved in thiol ester formation mutated to serines, which appeared structurally homologous to a2 M-TR. This demonstrates that the four highly labile thiol esters alone maintain the a2 M-N structure, while the ‘closed trap’ formed by a2 M-TR is a more stable structural form. ^ Half-transformed a2 M ( a2 M-HT), with cleaved bait regions and thiol esters in only two of its four subunits, provides an important structural link between a2 M-N and a2 M-TR. A comparison with a2 M-N showed the two proteinase-entrapping domains were above and below the plane bisecting the long axis. Both a2 M-N and a2 M-TR consist of two dense, oppositely twisted strands with significant interconnections, indicating that the structural change involves a rotation of these strands. In a2 M-HT these strands were partially untwisted with large central openings, revealing the manner in which the proteinase enters the internal cavity of a2 M. ^ In reconstructions of a2 M-N, a2 M-HT and a2 M-TR labeled with a monoclonal Fab, the Fabs were located on distal ends of each constitutive strand, demonstrating an anti-parallel arrangement of the subunits. Separation between the top and bottom pairs of Fabs was nearly the same on all structures, but the pairs were rotated about the long axis. Taken together, these results indicate that upon proteinase cleavage the two strands in a2 M-N separate. The proteinase enters the structure, while the strands re-twist to encage it. In a2 M-TR, which displays receptor-binding arms, more than two subunits are transformed as strands in the transformed half of a2 M-HT were not separated. ^

An inhibition ELISA to determine alpha macroglobulin levels in mouse plasma

A sensitive method for quantifying mouse plasma alpha-macroglobulins (AM) using an inhibition ELISA is described. AM are important plasmaproteinase inhibitors that possibly act also as immunomodulatory molecules. The standard protocol develope in our experiments involves coating well with 10 µg/ml A2M in carbonate buffer, followed by incubation with a 1:1 (v/v) mixture of the plasma to be tested (diluted 1/1000) and goat anti-AM (diluted 1/1250). This is followed by further incubation, first with the enzyme-conjugated antibody and with the substrate prior to the reading of absorbance levels of the reaction products. Standard curve samples must be included in each plate, employing known amounts of the purified Murine Alpha-2-Macroglobulin (MuA2M) used for coating, with concentrations ranging from 0.001 to 10 µg/ml. Using test samples in triplicates and a 6-point standard curve in a single ELISA plate, 25 plasma samples can be tested accurately. The method offers an useful tool for establishing AM levelsin small samples of mouse plasma.

Cardiovascular responses to microinjection of noradrenaline into the medial amygdaloid nucleus of conscious rats result from alpha(2)-receptor activation and vasopressin release

The medial amygdaloid nucleus (MeA) is involved in the modulation of physiological and behavioral processes, as well as regulation of the autonomic nervous system. Moreover, MeA electrical stimulation evokes cardiovascular responses. Thus, as noradrenergic receptors are present in this structure, the present study tested the effects of local noradrenaline (NA) microinjection into the MeA on cardiovascular responses in conscious rats. Moreover, we describe the types of adrenoceptor involved and the peripheral mechanisms involved in the cardiovascular responses. Increasing doses of NA (3, 9, 27 or 45 nmol/100 nL) microinjected into the MeA of conscious rats caused dose-related pressor and bradycardic responses. The NA cardiovascular effects were abolished by local pretreatment of the MeA with 10 nmol/100 nL of the specific alpha(2)-receptor antagonist RX821002, but were not affected by local pretreatment with 10 nmol/100 nL of the specific alpha(1)-receptor antagonist WB4101. The magnitude of pressor response evoked by NA microinjected into the MeA was potentiated by intravenous pretreatment with the ganglion blocker pentolinium (5 mg/kg), and blocked by intravenous pretreatment with the selective V(1)-vasopressin antagonist dTyr(CH(2))(5)(Me)AVP (50 mu g/kg). In conclusion, our results show that microinjection of NA into the MeA of conscious rats activates local alpha(2)-adrenoceptors, evoking pressor and bradycardic responses, which are mediated by vasopressin release.

Both alpha 1 and alpha 2-adrenoceptors mediate the cardiovascular responses to noradrenaline microinjected into the bed nucleus of the stria terminal of rats

Background and purpose: We have previously shown that noradrenaline microinjected into the bed nucleus of stria terminalis (BST) elicited pressor and bradycardiac responses in unanaesthetized rats. In the present study, we investigated the subtype of adrenoceptors that mediates the cardiovascular response to noradrenaline microinjection into the BST. Experimental approach: Cardiovascular responses following noradrenaline microinjection into the BST of male Wistar rats were studied before and after BST pretreatment with different doses of the selective alpha(1)-adrenoceptor antagonist WB4101, the alpha(2)-adrenoceptor antagonist RX821002, the combination of WB4101 and RX821002, the non-selective beta-adrenoceptor antagonist propranolol, the selective beta(1)-adrenoceptor antagonist CGP20712 or the selective beta(2)-adrenoceptor antagonist ICI118,551. Key results: Noradrenaline microinjected into the BST of unanaesthetized rats caused pressor and bradycardiac responses. Pretreatment of the BST with different doses of either WB4101 or RX821002 only partially reduced the response to noradrenaline. However, the response to noradrenaline was blocked when WB4101 and RX821002 were combined. Pretreatment with this combination also shifted the resulting dose-effect curve to the left, clearly showing a potentiating effect of this antagonist combination. Pretreatment with different doses of either propranolol or CGP20712 increased the cardiovascular responses to noradrenaline microinjected into the BST. Pretreatment with ICI118,551 did not affect cardiovascular responses to noradrenaline. Conclusion and implications: The present results indicate that alpha(1) and alpha(2)-adrenoceptors mediate the cardiovascular responses to noradrenaline microinjected into the BST. In addition, they point to an inhibitory role played by the activation of local beta(1)-adrenoceptors in the cardiovascular response to noradrenaline microinjected into the BST.

BED NUCLEUS OF THE STRIA TERMINALIS alpha(1)- AND alpha(2)-ADRENOCEPTORS DIFFERENTIALLY MODULATE THE CARDIOVASCULAR RESPONSES TO EXERCISE IN RATS

Dynamic exercise evokes sustained blood pressure and heart rate (HR) increases. Although it is well accepted that there is a CNS mediation of cardiovascular adjustments during dynamic exercise, information on the role of specific CNS structures is still limited. The bed nucleus of the stria terminalis (BST) is involved in exercise-evoked cardiovascular responses in rats. However, the specific neurotransmitter involved in BST-related modulation of cardiovascular responses to dynamic exercise is still unclear. In the present study, we investigated the role of local BST adrenoceptors in the cardiovascular responses evoked when rats are submitted to an acute bout of exercise on a rodent treadmill. We observed that bilateral microinjection of the selective alpha 1-adrenoceptor antagonist WB4101 into the BST enhanced the HR increase evoked by dynamic exercise without affecting the mean arterial pressure (MAP) increase. Bilateral microinjection of the selective alpha 2-adrenoceptor antagonist RX821002 reduced exercise-evoked pressor response without changing the tachycardiac response. BST pretreatment with the nonselective beta-adrenoceptor antagonist propranolol did not affect exercise-related cardiovascular responses. BST treatment with either WB4101 or RX821002 did not affect motor performance in the open-field test, which indicates that effects of BST adrenoceptor antagonism in exercise-evoked cardiovascular responses were not due to changes in motor activity. The present findings are the first evidence showing the involvement of CNS adrenoceptors in cardiovascular responses during dynamic exercise. Our results indicate an inhibitory influence of BST alpha 1-adrenoceptor on the exercise-evoked HR response. Data also point to a facilitatory role played by the activation of BST alpha 2-adrenoceptor on the pressor response to dynamic exercise. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Effect of chronic morphine treatment on alpha(2)-adrenoceptor mediated autoinhibition of transmitter release from sympathetic varicosities of the mouse vas deferens

1 The effect of chronic morphine treatment (CMT) on sympathetic innervation of the mouse vas deferens and on alpha (2)-adrenoceptor mediated autoinhibition has been examined using intracellular recording of excitatory junction potentials (EJPs) and histochemistry. 2 In chronically saline treated (CST) preparations. morphine (1 muM) and the alpha (2)-adrenoceptor agonist (clonidine, 1 muM) decreased the mean amplitude of EJPs evoked with 0.03 Hz stimulation by 81+/-8% (n=16) and 92+/-6% (n=7) respectively. In CMT preparations, morphine (1 muM) and clonidine (1 muM) decreased mean EJP amplitude by 68+/-8% (n = 7) and 79+/-8% (n = 7) respectively. 3 When stimulating the sympathetic axons at 0.03 Hz. the mean EJP amplitude recorded from smooth muscles acutely withdrawn from CMT was four times greater than for CST smooth muscles (40.7+/-3.8 mV, n = 7 compared with 9.9+/-0.3 mV, n = 7). 4 Part of the increase in mean EJP amplitude following CMT was produced by a 31% increase in the density of sympathetic axons and varicosities innervating the smooth muscle. 5 Results from the present study indicate that the effectiveness of alpha (2)-adrenocrptor mediated autoinhibition is only slightly reduced in CMT preparations. Most of the cross tolerance which develops between morphine, clonidine and alpha (2)-adrenoceptor mediated autoinhibition occurs as a consequence of increased efficacy of neuromuscular transmission which is produced by an increase in the probability of transmitter release and an increase in the density of sympathetic innervation.

Unravelling the role of alpha 2,6 sialic acid on mouse dentritic cells functions

RESUMO: As células dendríticas (CDs) são fundamentais na imunomodulação e iniciação de respostas imunes adaptativas, enquanto os ácidos siálicos (Sias) são potenciais imunomoduladores. Estas células expressam níveis elevados da sialiltransferase ST6Gal-1, que transfere Sias para a posição terminal de oligossacáridos. De facto, a maturação de CDs está associada a uma diminuição da sialilação na sua superfície celular. Apesar de ter função biológica desconhecida, a forma solúvel, extracelular de ST6Gal-1 aumenta em cancros e inflamação. Ainda assim, esta foi recentemente identificada como moduladora da hematopoiese. Considerando o importante papel das CDs na iniciação de respostas anticancerígenas, uma ligação entre a sialilação extrínseca induzida por ST6Gal-1 extracelular e o seu papel na modulação de CDs deve ser identificada. Neste trabalho hipotetizou-se que a sialilação α2,6 extrínseca de CDs diminui o seu perfil de maturação mediante ativação por lipopolissacarídeo (LPS). O objetivo principal foi sialilar extrinsecamente em α2,6 CDs da medula óssea de murganhos, avaliando os seus perfis de maturação e de libertação de citocinas, após estimulação com LPS (por Citometria de Fluxo e ELISA, respetivamente). Ao contrário da hipótese, o perfil celular não foi modulado, usando várias abordagens. Por outro lado, a consequência da falta de α2,6 Sias na maturação de CDs foi avaliada analisando: 1) CDs da medula óssea de murganhos tratadas com sialidase, 2) CDs da medula óssea e 3) CDs das vias aéreas, ambas de murganhos deficientes em ST6Gal-1, comparando com a estirpe selvagem. Estes resultados sugerem que a perta total de α2,6 Sias se relaciona com o aumento da expressão do complexo de histocompatibilidade principal de classe II. Apesar de controverso, é provável existirem mecanismos inerentes à ativação por LPS, reduzindo a eficácia de ST6Gal-1 extracelular. Por outro lado, a modificação no perfil de CDs de murganhos deficientes em ST6Gal-1 poderá relacionar-se com uma predisposição para um estado inflamatório severo. Com isto, o trabalho desenvolvido abriu futuras linhas de investigação, nomeadamente explorar outros fatores envolvidos na (de)sialilação α2,6 de CDs, podendo ter impacto em imunoterapia com uso de CDs.--------------------------ABSTRACT: Dendritic cells (DCs) are vital for immunomodulation and the initiation of adaptive immune responses, whereas sialic acids (Sias) are potential immunomodulators. These cells express high levels of sialyltransferase ST6Gal-1, responsible for transferring Sias to the terminal position of oligosaccharide chains. Indeed, DCs’ maturation is associated with decreased cell surface sialylation. Although its biological significance is unknown, the soluble, extracellular form of ST6Gal-1 increases in cancers and inflammation. However, extracellular ST6Gal-1 was recently identified as modulator of hematopoiesis. Considering that DCs play a crucial role in the initiation of a productive anti-cancer immune response, a link between extrinsic sialylation by the extracellular ST6Gal-1 on DC function needs to be investigated. We hypothesize that extrinsic α2,6 sialylation of DCs diminishes their maturation features upon lipopolysaccharide (LPS) stimulation. The main goal was to extrinsically α2,6 sialylate mice bone marrow derived DCs (BMDCs) and to evaluate their maturation and cytokine profiles upon LPS stimulation (by Flow Cytometry and ELISA, respectively). Unlike the hypothesis, we observed that BMDCs’ profile is not modulated, even using several approaches. In contrast, the consequence of lacking cell surface α2,6 Sias in DC maturation was assessed by analysing: 1) sialidase treated BMDCs, 2) BMDCs from mice lacking ST6Gal-1 and 3) DCs from mice airways, comparing wild type with ST6Gal-1 knockout mice. These results suggest that overall lack in α2,6 Sias is related with increased expression of major histocompatibility class II (MHC-II). Although appearing to be controversial findings, other intracellular mechanisms might be occurring upon LPS-induced BMDC activation, probably reducing extracellular ST6Gal-1 effect. In opposite, the modification observed in DC profile of ST6Gal-1 knockout mice might be related to its predisposition to a more severe inflammatory status. With this, the developed work opened future lines of investigation, namely exploring other factors involved in α2,6 (de)sialylation of DC, which might have influence in immunotherapy using DCs.

Zinc-alpha 2-glycoprotein gene expression in adipose tissue is related with insulin resistance and lipolytic genes in morbidly obese patients.

OBJECTIVE Zinc-α(2) glycoprotein (ZAG) stimulates lipid loss by adipocytes and may be involved in the regulation of adipose tissue metabolism. However, to date no studies have been made in the most extreme of obesity. The aims of this study are to analyze ZAG expression levels in adipose tissue from morbidly obese patients, and their relationship with lipogenic and lipolytic genes and with insulin resistance (IR). METHODS mRNA expression levels of PPARγ, IRS-1, IRS-2, lipogenic and lipolytic genes and ZAG were quantified in visceral (VAT) and subcutaneous adipose tissue (SAT) of 25 nondiabetic morbidly obese patients, 11 with low IR and 14 with high IR. Plasma ZAG was also analyzed. RESULTS The morbidly obese patients with low IR had a higher VAT ZAG expression as compared with the patients with high IR (p = 0.023). In the patients with low IR, the VAT ZAG expression was greater than that in SAT (p = 0.009). ZAG expression correlated between SAT and VAT (r = 0.709, p<0.001). VAT ZAG expression was mainly predicted by insulin, HOMA-IR, plasma adiponectin and expression of adiponectin and ACSS2. SAT ZAG expression was only predicted by expression of ATGL. CONCLUSIONS ZAG could be involved in modulating lipid metabolism in adipose tissue and is associated with insulin resistance. These findings suggest that ZAG may be a useful target in obesity and related disorders, such as diabetes.

Constitutively active mutants of the alpha 2-adrenergic receptor.

We have mutated a single residue, Thr373 [corrected], in the C-terminal portion of the third intracellular loop of the alpha 2C10-adrenergic receptor into five different amino acids. In analogy with the effect of similar mutations in the alpha 1B- and beta 2-adrenergic receptors, these substitutions resulted in two major biochemical modifications: 1) increased constitutive activity of the alpha 2-adrenergic receptor leading to agonist-independent inhibition of adenylyl cyclase and 2) increased affinity of the receptor for binding agonist but not antagonists. The increased constitutive activity of the mutated alpha 2-adrenergic receptors could be inhibited by pertussis toxin, clearly indicating that it results from spontaneous ligand-independent receptor coupling to Gi. In contrast, the increased affinity of the mutant receptors for binding agonists was unaffected by pertussis toxin treatment, indicating that this is an inherent property of the receptors not dependent on interaction with Gi. Coexpression of the receptor mutants with the receptor-specific kinase, beta ARK1, indicated that the constitutively active alpha 2-adrenergic receptors are substrates for beta-adrenergic receptor kinase (beta ARK)-mediated phosphorylation even in the absence of agonist. These findings strengthen the idea that constitutively active adrenergic receptors mimic the "active" state of a G protein-coupled receptor adopting conformations similar to those induced by agonist when it binds to wild type receptors. In addition, these results extend the notion that in the adrenergic receptor family the C-terminal portion of the third intracellular loop plays a general role in the processes involved in receptor activation.

Role of alpha 2,3-sialyltransferases ST3Gal III and ST3Gal IV in pancreatic ductal adenocarcinoma

Este trabajo demuestra que los genes que codifican para los enzimas beta-galactosido alfa-2,3-sialiltransferasa 3 (ST3Gal III), y en menor medida beta-galactosido alfa-2,3-sialiltransferasa 4 (ST3Gal IV), están directamente implicados en etapas clave de la progresión tumoral como la adhesión, la migración y la formación de metástasis en las líneas de adenocarcinoma pancreático humano Capan-1 y MDAPanc-28. También, que las Especies Reactivas del Oxígeno (ROS) generadas durante los procesos de proliferación y diferenciación celular o debido a estímulos oxidantes externos, desempeñan un importante papel en el control de la síntesis de ST3Gal III y SLex, y por lo tanto en la regulación del fenotipo metastático. Además, junto al papel pro-adhesivo de la E-Selectina, este trabajo ha descrito efectos prometastáticos adicionales para esta molécula como inductora de la migración y de la secreción de VEGF a través de un mecanismo E-Selectina-SLex dependiente.