Cathepsin X cleavage of the beta2 integrin regulates talin-binding and LFA-1 affinity in T cells

T cell migration, essential for immune surveillance and response, is mediated by the integrin LFA-1. CatX, a cysteine carboxypeptidase, is involved in the regulation of T cell migration by interaction with LFA-1. We show that sequential cleavage of C-terminal amino acids from the β(2) cytoplasmic tail of LFA-1, by CatX, enhances binding of the adaptor protein talin to LFA-1 and triggers formation of the latter's high-affinity form. As shown by SPR analysis of peptides constituting the truncated β(2) tail, the cleavage of three C-terminal amino acids by CatX resulted in a 1.6-fold increase of talin binding. Removal of one more amino acid resulted in a 2.5-fold increase over the intact tail. CatX cleavage increased talin-binding affinity to the MD but not the MP talin-binding site on the β(2) tail. This was shown by molecular modeling of the β(2) tail/talin F3 complex to be a result of conformational changes affecting primarily the distal-binding site. Analysis of LFA-1 by conformation-specific mAb showed that CatX modulates LFA-1 affinity, promoting formation of high-affinity from intermediate-affinity LFA-1 but not the initial activation of LFA-1 from a bent to extended form. CatX post-translational modifications may thus represent a mechanism of LFA-1 fine-tuning that enables the trafficking of T cells.     

Chemokines and Chemokine Receptors： Their Manifold Roles in Homeostasis and Disease

Chemokines are a superfamily of small proteins that bind to G protein-coupled receptors on target cells and were originally discovered as mediators of directional migration of immune cells to sites of inflammation and injury. In recent years, it has become clear that the function of chemokines extends well beyond the role in leukocyte chemotaxis. They participate in organ development, angiogenesis/angiostasis, leukocyte trafficking and homing, tumorigenesis and metastasis, as well as in immune responses to microbial infection. Therefore, chemokines and their receptors are important targets for modulation of host responses in pathophysiological conditions and for therapeutic intervention of human diseases.     

Chemokines: roles in leukocyte development,trafficking, and effector function

Chemokines, representing a large superfamily of 8- to 15-kd proteins, were originally discovered through their ability to recruit various cell types into sites of inflammation. It is now clear that these molecules play a much wider role in immune homeostasis, playing key roles in driving the maturation, homing, and activation of leukocytes. In this review we analyze the roles chemokines play in the development, recruitment, and activation of leukocytes. Because signaling from the receptors drives these processes, signal transduction from chemokine receptors will also be reviewed. Taken together, we highlight the various points at which chemokines contribute to allergic inflammation and at which their targeting might contribute to new therapies for type I hypersensitivity reactions.     

In vitro regulation of beta1 and beta3 integrin subunits in endometrial epithelial cells from normal endometrium

OBJECTIVE: To evaluate the effect of prostaglandin E2 (PGE2) and interleukin-1beta (IL-1beta) on integrin expression. DESIGN Cultures of endometrial epithelial cells from normal endometrium. SETTING: All endometrial specimens were obtained from the Obstetrics and gynecology Department of the Catholic University, Rome, Italy. PATIENTS: Four patients were normal menstrual cycles undergoing operative laparoscopy for non-endometrial problems. INTERVENTION: Endometrial samples were collected by uterine courettings. MAIN OUTCOME MEASURE: Immunocytochemistry for beta1 and beta3 integrin subunits. RESULTS: PGE2 clearly enhances both beta1 and beta3 integrin subunit expression. IL-1beta seem to slightly increase only beta3 subunit expression. CONCLUSIONS: In light of the critical role played by eicosanoids in endometrial differentiation, we suggest that PGE2 is also involved in local paracrine regulation of integrin expression.     

Separate roles for beta2- and beta3-adrenoceptors in memory consolidation

Consolidation of a labile memory which would not normally be stored can be achieved by intracerebral administration of noradrenaline. In a series of experiments using discriminated, one trial passive avoidance learning with the day-old chick, the effect of noradrenaline has been shown to be due to actions at different subtypes of adrenoceptors. The effect of noradrenaline is dose-dependent, with a moderate dose producing memory consolidation. However, higher doses of noradrenaline (0.3-10 nmol/hemisphere) prevent consolidation, an effect not seen with isoprenaline suggesting that these doses stimulate alpha-adrenoceptors. The promotion of memory consolidation by noradrenaline or isoprenaline at low doses was attributable to beta3-adrenoceptors and at medium doses to beta2-adrenoceptors. At higher doses of noradrenaline, there was alpha1-adrenoceptor-mediated inhibition of memory consolidation. Consolidation can also be achieved by administration of either beta2- or beta3-adrenoceptor agonists at specific times after training. Although these two adrenoceptors both promoted memory consolidation, there was a differential action on the stages of memory formation. The dose-response curve to the beta3- and the beta2-agonists was shifted by the appropriate antagonist but not by the antagonist at the other beta-adrenoceptor. Although beta1-adrenoceptors are present in chick brain, they do not seem to have a role in memory formation. These results explain why noradrenaline, acting at different adrenoceptors, can have different effects on memory formation with memory being either consolidated or inhibited depending on the dose. The findings also demonstrate a role in memory formation for beta3-adrenoceptors found in the brain. Agonists acting specifically at beta2- or beta3-adrenoceptors may be of value in diseases involving cognitive impairment.     

Cytokine regulation of IL-12 receptor beta2 expression: differential effects on human T and NK cells

The biological activities of IL-12 are mediated through a specific, high-affinity receptor composed of IL-12 receptor(R)beta1 and IL-12Rbeta2 subunits that exist primarily on T and NK cells. Remarkably, the expression of IL-12Rbeta2 on CD4(+) T cells in mouse and humans appears to be differentially regulated by IFN-gamma and IFN-alpha, respectively. Using an antibody specific for the human IL-12Rbeta2 subunit, the effect of IFN-gamma, IFN-alpha, IL-12 and IL-2 on the regulation of IL-12R expression and IL-12 responsiveness of human T and NK cells was assessed. The presence of IFN-alpha or IFN-gamma in cultures enhanced IL-12Rbeta2 expression of CD4(+) and CD8(+) T cells. The enhancing effect of IFN-alpha and IFN-gamma was independent of endogenous IL-12. Furthermore, the clearest effects of IFN-alpha and IFN-gamma on IL-12Rbeta2 expression on T cells were seen by abrograting the inhibition induced by the presence of IL-4 in cultures. In contrast to T cells, IFN-alpha and IFN-gamma had little effect on regulating IL-12Rbeta2 expression on human NK cells. Taken together, these data show that there is differential regulation of IL-12Rbeta2 expression by IFN-alpha and IFN-gamma on human T and NK cells.     

Contrasting roles for beta1, beta2 and beta3-adrenoceptors in memory formation in the chick

Noradrenaline plays distinct roles in the modulation and consolidation of memory for one-trial, discriminated, avoidance learning in the chick. We have previously shown that activation of beta2-, beta3- and alpha1-adrenoceptors (ARs) by injection into the multimodal forebrain association region (intermediate medial hyperstriatum ventrale [IMHV] or intermediate medial mesopallium [IMM]) is involved in the consolidation of memory 30 min after training and that activation of alpha2-ARs in the caudate putamen plays a role in the reinforcement of memory leading to consolidation in the IMM (IMHV). In this paper we provide evidence that noradrenaline acts at beta1-ARs in the basal ganglia (lobus parolfactorius or medial striatum) in short-term memory processing immediately post-training and demonstrate inhibition of memory by selective AR antagonists at particular times in the sequential memory processing sequence after training. These results support separate roles for beta2- and beta3-ARs in memory consolidation. Our studies suggest that, as a consequence of the learning experience, noradrenaline acts in different brain regions and at different times in memory processing, to enhance memory through distinct populations of ARs.     

Expression of cell adhesion molecules and their beta1 and beta2 integrin ligands in human liver peliosis

The expression of the following cell adhesion molecules and their beta1 and beta2 integrin ligands was investigated in the liver tissue from 3 patients with non-bacillar peliosis using light and electron microscope immunohistochemistry: intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, platelet endothelial cell adhesion molecule-1 (PECAM-1), leukocyte function-associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1), and very late antigen-4 (VLA-4). We found a parallel enhancement of the adhesion molecules expression in the dilated sinusoids and cavities in all 3 cases with peliosis. Mononuclear blood cells were detected in the sinusoids and sometimes perisinusoidally. These cells were mainly ICAM-1-, LFA-1-, and VLA-4-positive. At the ultrastructural level, ICAM-1-positive immune deposits were observed on the membrane of sinusoidal endothelial cells, Kupffer cells, and hepatocytes. The expression of cell adhesion molecules on liver sinusoids in peliosis is probably triggered by factors released from damaged endothelial cells and hepatocytes. The prevalence of the ICAM-1/LFA-1 and VCAM-1/VLA-4 patterns of mononuclear blood cell/sinusoidal cell interactions could support the macrophage-induced or lymphocyte-induced type of liver injury. PECAM-1 was also included in the non-specific immune response in peliosis. The presence of erythrostasis or thrombosis in liver sinusoids could participate in the induction of adhesion molecule expression in peliosis.     

Blood flow and permeability changes in the immune lymphocyte transfer reaction.

Blood flow (133Xe clearance) and plasma exudation ([133I]HSA) have been measured in the immune lymphocyte transfer (ILT) reaction and skin grafts in rabbits. Injection of sensitised lymphocytes produced a dose-related increase in plasma exudation and blood flow at 48 hr, reached a maximum at day 3 and faded from day 5 to 8. There was an increased blood flow and plasma exudation on day 4 after grafting autografts and homografts, but the increase in plasma exudation was significantly higher in homografts. In the ILT reaction (48 hr) and the homografts (4 days) but not in autografts, prostaglandin synthetase inhibition caused a significant reduction in the increased blood flow, but did not abolish it nor did they affect the increased plasma exudation. It is concluded that the ILT reaction is a suitable model for the study of mediators of the vascular effects of the early phase of the skin graft reaction. The present experiments suggest that the vasodilatation is partly due to prostaglandin formation, but part of the vasodilatation and all the plasma exudation are mediated by substances other than prostaglandins.     

Expression of integrin alpha5 and integrin beta4 and their extracellular ligands fibronectin and laminin in human decidua during early pregnancy and its sex steroid-mediated regulation

The reorganization of the human endometrium is termed decidualization, which includes endometrial cell proliferation, differentiation, integrin switching and extracellular matrix (ECM) remodeling during early pregnancy. The present study aimed to investigate distribution patterns, staining intensity and sex steroid-mediated regulation of integrin alpha5 (CD49e), integrin beta4 (CD49f) expression and their ligands fibronectin and laminin during decidualization. Human tissue samples were evaluated in two groups, those collected in early days and those collected in advanced days of the first trimester. Correlating immunostaining was found between laminin and integrin beta4, and between fibronectin and integrin alpha5. The expression of fibronectin was higher than that of laminin in the early days (p < 0.05). Temporal and spatial immunostaining of integrin beta4 and alpha5 in the apical pole of luminal and glandular cells was observed as pregnancy progressed (p < 0.05). In vitro results showed that human chorionic gonadotropin (hCG) stimulated laminin expression, downregulated integrin beta4 expression, whereas estradiol decreased fibronectin expression by Ishikawa cells. hCG suppressed fibronectin expression in endometrial stromal cells in culture. Our results suggest that fibronectin is responsible for induction of decidual cell differentiation, and different temporal and spatial expression of the integrins may play a role in implantation. Our in vitro results suggest that regulation of extracellular matrix remodeling and integrin switching are at least partially regulated by reproductive hormones.     

去乙酰化酶Sirtuins在干细胞功能调节中的作用及前景

BACKGROUND:Efficacy of stem cell therapy is considerably influenced by oxidative stress. Sirtuin (SIRT) family of mammals is an important deacetylation and antioxidant enzyme that can regulate endogenous antioxidant activities in stem cells and cell cycle related signaling pathways to reduce the damage and enhance the viability of stem cells. OBJECTIVE:To review the regulating function and mechanism of SIRT family. METHODS:A computer-based search of Web of Science, PubMed and CNKI from 1990 to 2015 was performed for relevant articles about SIRT and stem cell oxidative stress, using the key words of “SIRT, stem cell, oxidative stress, molecular mechanisms” in English and Chinese, respectively. After eliminating literatures which have poor authority or have similar contents, 55 articles were involved. RESULTS AND CONCLUSION:NAD⁺-dependent SIRT family is the key enzyme for deacetylation of histones and other proteins. It plays vital regulation roles in metabolism, genomic stability, DNA damage/repair, and chromatin remodeling/stress reaction. Progress in the SIRT-targeted stem cell research will definitely provide more clues for clinical stem cell transplantation therapy.     

The quantification of hCLCA2 and colocalisation with integrin beta4 in stratified human epithelia

Human calcium-activated chloride channel 2 (hCLCA2) belongs to a family of multifunctional proteins and is localised mainly in basal cells of squamous epithelia. However, its function is still not fully understood. Relative amounts of hCLCA2 were analysed using real-time PCR in several human epithelial tissues and tissues expressing high amounts were identified. These tissues then underwent double immunolabelling with anti-hCLCA2 antibodies and antibodies against the adhesion molecules integrin β4 and collagen VII and were visualised by fluorescence microscopy. Real-time PCR found hCLCA2 gene expression to be primarily associated with stratified squamous epithelia. Subsequent immunohistochemistry clearly demonstrated colocalisation between hCLCA2 and integrin β4. This study reports on a possible underlying relationship between hCLCA2 and stratified epithelia and the close association of hCLCA2 with basal cell adhesion molecules in normal tissue, suggesting it may play an important role in basal cell attachment in stratified epithelia.     

Interferons in autoimmune and inflammatory diseases: regulation and roles

Several lines of evidence strongly implicate type I interferons (IFN-α and β) and IFN-signaling in the pathogenesis of certain autoimmune inflammatory diseases. Accordingly, genome-wide association studies have identified polymorphisms in the type I IFN-signaling pathways. Other studies also indicate that a feed-forward loop of type I IFN production, which involves sensing of cytoplasmic nucleic acids by sensors, contributes to the development of immunopathology. In addition, a mutually positive regulatory feedback loop between type I IFNs and estrogen receptor-α may contribute to a gender bias, thus resulting in an increased production of type I IFNs and associated immunopathology in women. Increased levels of type I IFNs have numerous immunomodulatory functions for both the innate and adaptive immune responses. Given that the IFN-β also has some anti-inflammatory roles, identifying molecular links among certain genotypes, cytokine profiles, and associated phenotypes in patients with autoimmune inflammatory diseases is likely to improve our understanding of autoimmunity-associated pathogenesis and suboptimal outcomes following standard therapies.     

Activation-dependent changes in soluble fibronectin binding and expression of beta1 integrin activation epitopes in T cells: relationship to T cell adhesion and migration

The relationship between activation-dependent changes in beta1 integrin conformation, T cell adhesion to immobilized fibronectin, and T cell migration in vitro was analyzed in this study. Stimulation of Jurkat T cells and peripheral T cells with Mn(2+), the activating beta1 integrin-specific monoclonal antibody (mAb) TS2 /16, CD2, or CD28 stimulation led to increased adhesion, soluble fibronectin (FN) binding and expression of the activation epitope defined by the beta1 integrin mAb HUTS-21. Phorbol 12-myristate 13-acetate treatment increased adhesion, but not soluble FN binding or HUTS-21 epitope expression. In peripheral T cells, CD3 or CD7 stimulation also led to increased adhesion, soluble FN binding and HUTS-21 epitope expression. Soluble FN blocked peripheral T cell adhesion induced by Mn(2+) or TS2/16, but had no effect on adhesion induced by the other integrin-activating signals. In contrast, migration induced by TS2/16, CD2, CD3, CD7 or CD28 stimulation was blocked by excess soluble FN. Phosphoinositide 3-OH kinase (PI 3-K) inhibitors blocked receptor-mediated increases in cell adhesion, but not soluble FN binding or HUTS-21 expression. Migration was similarly unaffected by PI 3-K inhibitors, with the exception of CD7- and CD28-induced migration, which was specifically blocked by LY294,002. These results suggest that activation-dependent changes in beta1 integrin conformation are PI 3-K-independent and are involved in T cell migration but not adhesion.     

Beyond immediate hypersensitivity: evolving roles for IgE antibodies in immune homeostasis and allergic diseases

Immunoglobulin E (IgE) antibodies have long been recognized as the antigen-specific triggers of allergic reactions. This review briefly introduces the established functions of IgE in immediate hypersensitivity and then focuses on emerging evidence from our own investigations as well as those of others that IgE plays important roles in protective immunity against parasites and exerts regulatory influences in the expression of its own receptors, FcεRI and CD23, as well as controlling mast cell homeostasis. We provide an overview of the multifaceted ways in which IgE antibodies contribute to the pathology of food allergy and speculate regarding potential mechanisms of action of IgE blockade.     

The sequence of changes in blood flow and lymphocyte influx to stimulated rat lymph nodes.

The rat popliteal lymph node was studied from 1 hr to 8 days after the footpad injection of either sheep erythrocytes or syngeneic rat erythrocytes. The following were measured relative to the contralateral (unstimulated) lymph node: (i) blood flow; (ii) lymph node weight; (iii) influx of lymphocytes from the blood; (iv) [3H]-thymidine incorporation; (v) [35S]-sulphate incorporation into macromolecular form (chiefly by high endothelial venules). After the arrival of sheep erythrocytes all five quantities showed substantial increases which began in a definite sequence. The blood flow started to rise first and may have been the main factor contributing to the later increase in lymphocyte influx. Increased sulphate incorporation began later than the rise in lymphocyte influx. After the injection of rat erythrocytes a small increase in lymphocyte influx was found without a corresponding increase in blood flow. In rats irradiated before the footpad injections lymphocyte influx increased three-fold after sheep erythrocytes, rat erythrocytes or PBS, again without a corresponding increase in blood flow. Thus while variation in blood flow to high endothelial venules is one important factor in determining the supply of lymphocytes to the lymph node other factors are operative in certain situations.