Development of New Potential Inhibitors of ß1 Integrins through In Silico Methods-Screening and Computational Validation.

Integrins are transmembrane receptors that play a critical role in many biological processes which can be therapeutically modulated using integrin blockers, such as peptidomimetic ligands. This work aimed to develop new potential ß1 integrin antagonists using modeled receptors based on the aligned crystallographic structures and docked with three lead compounds (BIO1211, BIO5192, and TCS2314), widely known as α4ß1 antagonists. Lead-compound complex optimization was performed by keeping intact the carboxylate moiety of the ligand, adding substituents in two other regions of the molecule to increase the affinity with the target. Additionally, pharmacokinetic predictions were performed for the ten best ligands generated, with the lowest docking interaction energy obtained for α4ß1 and BIO5192. Results revealed an essential salt bridge between the BIO5192 carboxylate group and the Mg2+ MIDAS ion of the integrin. We then generated more than 200 new BIO5192 derivatives, some with a greater predicted affinity to α4ß1. Furthermore, the significance of retaining the pyrrolidine core of the ligand and increasing the therapeutic potential of the new compounds is emphasized. Finally, one novel molecule (1592) was identified as a potential drug candidate, with appropriate pharmacokinetic profiles, similar dynamic behavior at the integrin interaction site compared with BIO5192, and a higher predicted affinity to VLA-4.

Enhanced Migratory Capacity of T Lymphocytes in Severe Chagasic Patients Is Correlated With VLA-4 and TNF-α Expression.

Trypanosoma cruzi infection in humans leads to progression to chronic chagasic myocarditis (CCM) in 30% of infected individuals, paralleling T cell inflammatory infiltrates in the heart tissue. T-cell trafficking into the hearts of CCM patients may be modulated by in situ expression of chemotactic or haptotactic molecules, as the chemokine CXCL12, the cytokine tumor necrosis factor-alpha (TNF-α), and extracellular matrix proteins (ECM), such as fibronectin. Herein we evaluated the expression of fibronectin, CXCL12, and TNF-α in the myocardial tissue of T. cruzi seropositive (asymptomatic or with CCM), as well as seronegative individuals as healthy controls. Hearts from CCM patients exhibited enhanced expression of these three molecules. CXCL12 and TNF-α serum levels were also increased in CCM individuals. We then evaluated T lymphocytes from chronic chagasic patients by cytofluorometry, in terms of membrane expression levels of molecules involved in cell activation and cell migration, respectively, HLA-DR and the VLA-4 (very late antigen-4, being one integrin-type fibronectin receptor). Indeed, the expression of HLA-DR and VLA-4 was enhanced on T lymphocytes from chagasic patients, especially in the CCM group. To further approach the dynamics of T cell migratory events, we performed fibronectin-, TNF-α-, and CXCL12-driven migration. Peripheral blood mononuclear cells (PBMCs) and T cells from CCM patients presented an ex vivo enhanced migratory capacity driven by fibronectin alone when this ECM protein was placed in the membrane of transwell migration chambers. When TNF-α was previously placed upon fibronectin, we observed a further and significant increase in the migratory response of both PBMCs and T lymphocytes. Overall, these data suggest the existence in patients with chronic Chagas disease of a cardiac inflammatory infiltrate vector that promotes the recruitment and accumulation of activated T cells, driven in part by enhanced tissue expression of fibronectin and TNF-α, as well as the respective corresponding VLA-4 and TNF receptors.

An Overview of the α4ß1 Integrin and the Potential Therapeutic Role of its Antagonists.

This article presents a simplified view of integrins with emphasis on the α4 (α4ß1/VLA-4) integrin. Integrins are heterodimeric proteins expressed on the cell surface of leukocytes that participate in a wide variety of functions, such as survival, growth, differentiation, migration, inflammatory responses, tumour invasion, among others. When the extracellular matrix is degraded or deformed, cells are forced to undergo responsive changes that influence remodelling during physiological and pathological events. Integrins recognize these changes and trigger a series of cellular responses, forming a physical connection between the interior and the outside of the cell. The communication of integrins through the plasma membrane occurs in both directions, from the extracellular to the intracellular (outside-in) and from the intracellular to the extracellular (inside-out). Integrins are valid targets for antibodies and small-molecule antagonists. One example is the monoclonal antibody natalizumab, marketed under the name of TYSABRI®, used in the treatment of recurrent multiple sclerosis, which inhibits the adhesion of α4 integrin to its counter-receptor. α4ß1 Integrin antagonists are summarized here, and their utility as therapeutics are also discussed.

Airways exposure of bacterial superantigen SEB enhances bone marrow eosinophil population and facilitates its egress to blood and lung tissue.

BACKGROUND: Differentiation of bone marrow eosinophils (BM-EO) and its trafficking to peripheral blood and respiratory mucosa are a hallmark of inflammatory diseases. Staphylococcal enterotoxin B (SEB) has been shown to aggravate airways eosinophilic inflammation. This study aimed to investigate the effects of mouse airways SEB exposure on BM-EO population, as well as its adhesive properties and release of cytokines/chemokines that orchestrate BM-EO trafficking to lungs. METHODS: Male BALB/c mice were intranasally exposed to SEB (1 µg), and at 4, 16, 24 and 48 h thereafter, bone marrow (BM), circulating blood and bronchoalveolar lavage (BAL) fluid were collected. Levels of cytokines/chemokines and expressions of VLA-4 and CCR3 in BM were evaluated. Adhesion of BM to ICAM-1 and VCAM-1 were also evaluated. RESULTS: SEB exposure promoted a marked eosinophil influx to BAL at 16 and 24 h after exposure, which was accompanied by significant increases in counts of immature (16 h) and mature (4 to 48 h) forms of eosinophil in BM, along with blood eosinophilia (16 h). In BM, higher levels of eotaxin, IL-5, IL-4, IL-3 and IL-7 were detected at 16 to 48 h. SEB also significantly increased CCR3 expression and calcium levels in BM-EO, and enhanced the cell adhesion to ICAM-1 (24 h) and ICAM-1 (48 h). CONCLUSION: Airways SEB exposure increases the number of eosinophils in BM by mechanisms involving a network of cytokine and chemokine release, facilitating the BM-EO adhesion to ICAM-1 and VCAM-1 to gain access to the peripheral blood and lung tissues.

CD49d Is Upregulated in Circulating T Lymphocytes from HTLV-1-Infected Patients.

INTRODUCTION: HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic progressive myelopathy associated with an inflammation of the central nervous system (CNS), being characterized by perivascular infiltration of inflammatory cells. HTLV-1-infected cells have the capacity to migrate through endothelial layers by enhancing adhesion receptor expression and corresponding ligands. T cells interact with the extracellular matrix via integrin receptors and these interactions affect both cell migration and proliferation. The importance of these interactions in retrovirus-induced diseases, however, remains less clear. METHODS: Herein we studied the expression of 3 integrin alpha chains (CD49d, CD49e, and CD49f) on the membrane of T-cell subsets in patients infected by HTLV-1, both HAM/TSP patients and oligo/asymptomatic subjects who were asymptomatic or presented slight manifestations related to the virus infection. RESULTS: We observed higher peripheral blood frequency of CD49dhiCD4+ and CD49dhiCD8+ T cells in HTLV-1-infected patients. CONCLUSION: Our findings suggest that the increased expression of adhesion molecules, such as CD49d on T lymphocytes from HTLV-1-infected patients may contribute to the pathogenesis of the disease, in both oligo/asymptomatic and HAM/TSP-infected subjects. Accordingly, it is conceivable that there is a potential use of CD49d as target for a therapeutic approach aiming at blocking migration of activated T cells from HTLV-1-infected patients into the CNS, thus avoiding the progression to HAM/TSP.

Interactions between thymic endothelial cells and thymocytes are influenced by growth hormone.

Growth hormone (GH), in addition to its classic actions on growth and metabolism in the body, exerts pleiotropic effects on the immune system, particularly on the thymus. The aim of this study was to evaluate the influence of GH on the interactions between mature thymocytes and the thymic endothelium involved in the migratory process. To this end, fresh thymocytes (C57BL/6 mice) and the thymic endothelial cell line (tEnd.1) were used. In the cell adhesion assay, the GH-treated thymocytes adhered more to tEnd.1 cells. Additionally, there was an improvement in the deposition of fibronectin by tEnd.1 cells when co-cultured with GH-pre-treated thymocytes. Furthermore, GH induced thymocyte F-actin polymerization. In the transendothelial migration assay, a large number of GH-treated thymocytes, mainly the CD4-CD8+ subset, migrated towards the endothelium under the stimulus of insulin-like growth factor 1. In conclusion, we demonstrated the positive actions of GH in thymocyte/thymic endothelium interactions, including transendothelial migration.

Sphingosine-1-Phosphate Receptor 1 Is Involved in Non-Obese Diabetic Mouse Thymocyte Migration Disorders.

NOD (non-obese diabetic) mice spontaneously develop type 1 diabetes following T cell-dependent destruction of pancreatic β cells. Several alterations are observed in the NOD thymus, including the presence of giant perivascular spaces (PVS) filled with single-positive (SP) CD4⁺ and CD8⁺ T cells that accumulate in the organ. These cells have a decreased expression of membrane CD49e (the α5 integrin chain of the fibronectin receptor VLA-5 (very late antigen-5). Herein, we observed lower sphingosine-1-phosphate receptor 1 (S1P1) expression in NOD mouse thymocytes when compared with controls, mainly in the mature SP CD4⁺CD62Lhi and CD8⁺CD62Lhi subpopulations bearing the CD49e− phenotype. In contrast, differences in S1P1 expression were not observed in mature CD49e⁺ thymocytes. Functionally, NOD CD49e− thymocytes had reduced S1P-driven migratory response, whereas CD49e⁺ cells were more responsive to S1P. We further noticed a decreased expression of the sphingosine-1-phosphate lyase (SGPL1) in NOD SP thymocytes, which can lead to a higher sphingosine-1-phosphate (S1P) expression around PVS and S1P1 internalization. In summary, our results indicate that the modulation of S1P1 expression and S1P/S1P1 interactions in NOD mouse thymocytes are part of the T-cell migratory disorder observed during the pathogenesis of type 1 diabetes.

Ocorrência e fatores de risco da infecção pelo vírus da língua azul em bovinos no Estado de Pernambuco / Occurrence and risk factors of the Bluetongue Virus infeccion in cattle in Pernambuco state, Brazil

Objetivou-se com este estudo determinar os aspectos epidemiológicos da infecção pelo Vírus da Língua Azul (VLA) em bovinos leiteiros na microrregião de Garanhuns, Estado de Pernambuco, Brasil. Foram coletadas 384 amostras de soro de bovinos fêmeas em idade reprodutiva, procedentes de 20 propriedades dos 19 municípios que compõem a região. As amostras foram testadas com a prova de imunodifusão em gel de agarose (IDGA) para pesquisa de anticorpos anti-VLA. Observou-se ocorrência de 71,3% (274/384; IC 95% - 66,5% - 75,7%) de animais positivos. Em 100% das propriedades houve ao menos um animal soropositivo. Os fatores de risco identificados foram: presença de áreas alagadas (OR=11,8; p=0,001), não realizar controle de insetos (OR=2,1; p=0,033), rebanho aberto (OR=2,1; p=0,001) e utilização de inseminação artificial (OR=8,8; p=0,003). Este é o primeiro registro de detecção de anticorpos anti-VLA em bovinos no Estado de Pernambuco. Conclui-se que a infecção pelo VLA ocorre em bovinos na área estudada e sugere-se que medidas de controle baseadas no manejo higiênico-sanitário e biosseguridade sejam implantadas para evitar a propagação do vírus, tais como: eliminação de áreas alagadiças; controle de insetos; utilizar sêmen na inseminação artificial com atestado sanitário; realizar exames sorológicos ao adquirir animais.(AU)

The objective of this study was to determine epidemiological aspects of Bluetongue Virus (BTV) infection on dairy cattle in the Garanhuns microregion, Pernambuco state, Brazil. Three hundred eighty-four (384) serum samples of female bovines of reproductive age were collected from 20 farms of the 19 municipalities that make up the region. Samples were tested with the agarose gel immunodiffusion test (AGID) for anti-VLA antibody screening. There were 71.3% (274/384, 95% CI - 66.5% - 75.7%) positive animals. In 100% of the farms there was at least one seropositive animal. The risk factors identified were: presence of flooded areas (OR=11.8, p=0.001), absence of insect control (OR=2.1, p=0.033), open herd (OR=2.1; p=0.001) and use of artificial insemination (OR=8.8, p=0.003). This is the first record of detection of anti-BTV antibodies in cattle in Pernambuco state. It is concluded that BTV infection occurs in cattle in the studied area, and it is suggested that control measures based on hygienic-sanitary management and biosecurity are in place to prevent the spread of the virus, such as elimination of wetlands; Insect control; semen used in artificial insemination with health certificate; Serological tests when acquiring animals.(AU)

Ocorrência e fatores de risco da infecção pelo vírus da língua azul em bovinos no Estado de Pernambuco / Occurrence and risk factors of the Bluetongue Virus infeccion in cattle in Pernambuco state, Brazil

Objetivou-se com este estudo determinar os aspectos epidemiológicos da infecção pelo Vírus da Língua Azul (VLA) em bovinos leiteiros na microrregião de Garanhuns, Estado de Pernambuco, Brasil. Foram coletadas 384 amostras de soro de bovinos fêmeas em idade reprodutiva, procedentes de 20 propriedades dos 19 municípios que compõem a região. As amostras foram testadas com a prova de imunodifusão em gel de agarose (IDGA) para pesquisa de anticorpos anti-VLA. Observou-se ocorrência de 71,3% (274/384; IC 95% - 66,5% - 75,7%) de animais positivos. Em 100% das propriedades houve ao menos um animal soropositivo. Os fatores de risco identificados foram: presença de áreas alagadas (OR=11,8; p=0,001), não realizar controle de insetos (OR=2,1; p=0,033), rebanho aberto (OR=2,1; p=0,001) e utilização de inseminação artificial (OR=8,8; p=0,003). Este é o primeiro registro de detecção de anticorpos anti-VLA em bovinos no Estado de Pernambuco. Conclui-se que a infecção pelo VLA ocorre em bovinos na área estudada e sugere-se que medidas de controle baseadas no manejo higiênico-sanitário e biosseguridade sejam implantadas para evitar a propagação do vírus, tais como: eliminação de áreas alagadiças; controle de insetos; utilizar sêmen na inseminação artificial com atestado sanitário; realizar exames sorológicos ao adquirir animais.(AU)

The objective of this study was to determine epidemiological aspects of Bluetongue Virus (BTV) infection on dairy cattle in the Garanhuns microregion, Pernambuco state, Brazil. Three hundred eighty-four (384) serum samples of female bovines of reproductive age were collected from 20 farms of the 19 municipalities that make up the region. Samples were tested with the agarose gel immunodiffusion test (AGID) for anti-VLA antibody screening. There were 71.3% (274/384, 95% CI - 66.5% - 75.7%) positive animals. In 100% of the farms there was at least one seropositive animal. The risk factors identified were: presence of flooded areas (OR=11.8, p=0.001), absence of insect control (OR=2.1, p=0.033), open herd (OR=2.1; p=0.001) and use of artificial insemination (OR=8.8, p=0.003). This is the first record of detection of anti-BTV antibodies in cattle in Pernambuco state. It is concluded that BTV infection occurs in cattle in the studied area, and it is suggested that control measures based on hygienic-sanitary management and biosecurity are in place to prevent the spread of the virus, such as elimination of wetlands; Insect control; semen used in artificial insemination with health certificate; Serological tests when acquiring animals.(AU)

Flow Cytometry-Defined CD49d Expression in Circulating T-Lymphocytes Is a Biomarker for Disease Progression in Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) affects 1:3500-1:5000 male births, and is caused by X-linked mutations in the dystrophin gene, manifested by progressive muscle weakness and wasting due to the absence of dystrophin protein, leading to degeneration of skeletal muscle. DMD patients are clinically heterogeneous and the functional phenotype often cannot be correlated with the genotype. Therefore, defined reliable noninvasive biomarkers aiming at predicting if a given DMD child will progress more or less rapidly will be instrumental to better design inclusion of defined patients for future therapeutic assays. We recently showed that CD49d expression levels in blood-derived T-cell subsets can predict disease progression in DMD patients. Herein we describe in detail the methodology to be applied for defining, through four-color flow cytometry, the membrane expression levels of the CD49d (the α4 chain of the integrins α4ß1 and α4ß7) in circulating CD4+ and CD8+ T cell subsets. Since we have also shown that this molecule can also be placed as a potential target for therapeutics in DMD, we also describe the cell migration functional assay that can be applied to test potential CD49d inhibitors that can modulate their ability to cross endothelial or extracellular matrix (ECM) barriers.

Ocorrência e fatores de risco da infecção pelo vírus da língua azul em bovinos no Estado de Pernambuco

ABSTRACT: The objective of this study was to determine epidemiological aspects of Bluetongue Virus (BTV) infection on dairy cattle in the Garanhuns microregion, Pernambuco state, Brazil. Three hundred eighty-four (384) serum samples of female bovines of reproductive age were collected from 20 farms of the 19 municipalities that make up the region. Samples were tested with the agarose gel immunodiffusion test (AGID) for anti-VLA antibody screening. There were 71.3% (274/384, 95% CI - 66.5% - 75.7%) positive animals. In 100% of the farms there was at least one seropositive animal. The risk factors identified were: presence of flooded areas (OR=11.8, p=0.001), absence of insect control (OR=2.1, p=0.033), open herd (OR=2.1; p=0.001) and use of artificial insemination (OR=8.8, p=0.003). This is the first record of detection of anti-BTV antibodies in cattle in Pernambuco state. It is concluded that BTV infection occurs in cattle in the studied area, and it is suggested that control measures based on hygienic-sanitary management and biosecurity are in place to prevent the spread of the virus, such as elimination of wetlands; Insect control; semen used in artificial insemination with health certificate; Serological tests when acquiring animals.

RESUMO: Objetivou-se com este estudo determinar os aspectos epidemiológicos da infecção pelo Vírus da Língua Azul (VLA) em bovinos leiteiros na microrregião de Garanhuns, Estado de Pernambuco, Brasil. Foram coletadas 384 amostras de soro de bovinos fêmeas em idade reprodutiva, procedentes de 20 propriedades dos 19 municípios que compõem a região. As amostras foram testadas com a prova de imunodifusão em gel de agarose (IDGA) para pesquisa de anticorpos anti-VLA. Observou-se ocorrência de 71,3% (274/384; IC 95% - 66,5% - 75,7%) de animais positivos. Em 100% das propriedades houve ao menos um animal soropositivo. Os fatores de risco identificados foram: presença de áreas alagadas (OR=11,8; p=0,001), não realizar controle de insetos (OR=2,1; p=0,033), rebanho aberto (OR=2,1; p=0,001) e utilização de inseminação artificial (OR=8,8; p=0,003). Este é o primeiro registro de detecção de anticorpos anti-VLA em bovinos no Estado de Pernambuco. Conclui-se que a infecção pelo VLA ocorre em bovinos na área estudada e sugere-se que medidas de controle baseadas no manejo higiênico-sanitário e biosseguridade sejam implantadas para evitar a propagação do vírus, tais como: eliminação de áreas alagadiças; controle de insetos; utilizar sêmen na inseminação artificial com atestado sanitário; realizar exames sorológicos ao adquirir animais.

Staphylococcal enterotoxin A regulates bone marrow granulocyte trafficking during pulmonary inflammatory disease in mice.

Pulmonary neutrophil infiltration produced by Staphylococcal enterotoxin A (SEA) airway exposure is accompanied by marked granulocyte accumulation in bone marrow (BM). Therefore, the aim of this study was to investigate the mechanisms of BM cell accumulation, and trafficking to circulating blood and lung tissue after SEA airway exposure. Male BALB/C mice were intranasally exposed to SEA (1µg), and at 4, 12 and 24h thereafter, BM, circulating blood, bronchoalveolar lavage (BAL) fluid and lung tissue were collected. Adhesion of BM granulocytes and flow cytometry for MAC-1, LFA1-α and VLA-4 and cytokine and/or chemokine levels were assayed after SEA-airway exposure. Prior exposure to SEA promoted a marked PMN influx to BAL and lung tissue, which was accompanied by increased counts of immature and/or mature neutrophils and eosinophils in BM, along with blood neutrophilia. Airway exposure to SEA enhanced BM neutrophil MAC-1 expression, and adhesion to VCAM-1 and/or ICAM-1-coated plates. Elevated levels of GM-CSF, G-CSF, INF-γ, TNF-α, KC/CXCL-1 and SDF-1α were detected in BM after SEA exposure. SEA exposure increased production of eosinopoietic cytokines (eotaxin and IL-5) and BM eosinophil VLA-4 expression, but it failed to affect eosinophil adhesion to VCAM-1 and ICAM-1. In conclusion, BM neutrophil accumulation after SEA exposure takes place by integrated action of cytokines and/or chemokines, enhancing the adhesive responses of BM neutrophils and its trafficking to lung tissues, leading to acute lung injury. BM eosinophil accumulation in SEA-induced acute lung injury may occur via increased eosinopoietic cytokines and VLA-4 expression.

Airway exposure to staphylococcal enterotoxin A potentiates allergen-induced bone marrow eosinophilia and trafficking to peripheral blood and airways.

Bone marrow (BM) eosinopoiesis is a common feature during allergen exposure in atopic individuals. Airway exposure to staphylococcal superantigens aggravates allergic airway disease and increases the output of BM eosinophils. However, the exact mechanisms regulating eosinophil mobilization and trafficking to the peripheral circulation and airways remain to be elucidated. Therefore, this study aimed to investigate the mechanisms determining the BM eosinopoiesis in allergic mice under exposure to staphylococcal enterotoxin A (SEA). Ovalbumin (OVA)-sensitized male BALB/C mice were intranasally exposed to SEA (1 µg), and at 4, 12, 24, and 48 h later animals were challenged with OVA (10 µg, twice a day). Measurement of IL-5, eotaxin, and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels, flow cytometry for CCR3(+), VLA4(+), and CCR3(+)VLA4(+), as well as adhesion assays to VCAM-1 were performed in BM. Prior airway exposure to SEA time dependently increased the BM eosinophil number in OVA-challenged mice. Eosinophils gradually disappear from peripheral blood, being recruited over time to the airways, where they achieve a maximal infiltration at 24 h. SEA exposure increased the levels of IL-5 and eotaxin (but not GM-CSF) in BM of OVA-challenged mice. Marked increases in CCR3(+) and CCR3(+)VLA4(+) expressions in BM eosinophils of OVA-challenged mice were observed, an effect largely reduced by prior exposure to SEA. Adhesion of BM eosinophils to VCAM-1 was increased in OVA-challenged mice, but prior SEA exposure abrogated this enhanced cell adhesion. Accumulation of BM eosinophils by airway SEA exposure takes place through IL-5- and CCR3-dependent mechanisms, along with downregulation of CCR3/VL4 and impaired cell adhesion to VCAM-1.