Position of macula lutea and presence of proliferative vitreoretinopathy affect vitreous cytokine expression in rhegmatogenous retinal detachment

Our purpose was to evaluate the concentrations of vitreous cytokines in patients with rhegmatogenous retinal detachment (RRD). We hypothesized that patients with macula on RRD have lower levels of cytokines compared to patients with macula off RRD and proliferative vitreoretinopathy (PVR). Vitreous fluids were collected during 23G pars plana vitrectomy from 58 eyes of 58 patients. Indication for vitrectomy included macula off and macula on RRD, PVR, and idiopathic epiretinal membrane (ERM). A multiplex chemiluminescent immunoassay was performed to measure the concentrations of 48 cytokines, chemokines, and growth factors. Levels of HGF, IL-6, IL-8, IL-16, IFN-gamma, MCP-1, and MIF were significantly higher in all groups of retinal detachment compared to ERM. Levels of CTACK, eotaxin, G-CSF, IP-10, MIG, SCF, SCGF-beta, SDF-1alpha were significantly higher in PVR compared to macula on RRD and ERM. Levels of IL-1ra, IL-5, IL-9, M-CSF, MIP-1alpha, and TRIAL were significantly higher in PVR compared to macula on RRD. Our results indicate that the position of macula lutea and the presence of PVR significantly influence vitreous cytokine expression. The detected proteins may serve as biomarkers to estimate the possibility of PVR formation and may help to invent personalized therapeutic strategies to slow down or prevent PVR.

Characteristic Cytokine and Chemokine Profiles in Encephalitis of Infectious, Immune-Mediated, and Unknown Aetiology

Background

Encephalitis is parenchymal brain inflammation due to infectious or immune-mediated processes. However, in 15–60% the cause remains unknown. This study aimed to determine if the cytokine/chemokine-mediated host response can distinguish infectious from immune-mediated cases, and whether this may give a clue to aetiology in those of unknown cause.

Methods

We measured 38 mediators in serum and cerebrospinal fluid (CSF) of patients from the Health Protection Agency Encephalitis Study. Of serum from 78 patients, 38 had infectious, 20 immune-mediated, and 20 unknown aetiology. Of CSF from 37 patients, 20 had infectious, nine immune-mediated and eight unknown aetiology.

Results

Heat-map analysis of CSF mediator interactions was different for infectious and immune-mediated cases, and that of the unknown aetiology group was similar to the infectious pattern. Higher myeloperoxidase (MPO) concentrations were found in infectious than immune-mediated cases, in serum and CSF (p = 0.01 and p = 0.006). Serum MPO was also higher in unknown than immune-mediated cases (p = 0.03). Multivariate analysis selected serum MPO; classifying 31 (91%) as infectious (p = 0.008) and 17 (85%) as unknown (p = 0.009) as opposed to immune-mediated. CSF data also selected MPO classifying 11 (85%) as infectious as opposed to immune-mediated (p = 0.036). CSF neutrophils were detected in eight (62%) infective and one (14%) immune-mediated cases (p = 0.004); CSF MPO correlated with neutrophils (p<0.0001).

Conclusions

Mediator profiles of infectious aetiology differed from immune-mediated encephalitis; and those of unknown cause were similar to infectious cases, raising the hypothesis of a possible undiagnosed infectious cause. Particularly, neutrophils and MPO merit further investigation.

Increased type 1 chemokine expression in experimental Chagas disease correlates with cardiac pathology in beagle dogs

Chemokines and chemokine receptors interaction have presented important role in leukocyte migration to specific immune reaction sites. Recently, it has been reported that chemokine receptors CXC (CXCR3) and CC (CCR5) were preferentially expressed on Th1 cells while CCR3 and CCR4 were preferentially expressed on Th2 cells. This study evaluated the mRNA expression of type 1 and type 2 chemokine and chemokine receptors in the cardiac tissue of Beagle dogs infected with distinct genetic groups of Trypanosoma cruzi (Y, Berenice-78 and ABC strains) during acute and chronic phases. To analyze the correlation between chemokine and chemokine receptors expression and the development of heart pathology, the chronic infected animals were divided into groups, according to the parasite strain and based on the degree of heart damage: cardiac and indeterminate form of Chagas disease. Our results indicated that cardiac type1/2 chemokines and their receptors were partially dependent on the genetic diversity of parasites as well as the polarization of clinical forms. Also, dogs presenting cardiac form showed lower heart tissue mRNA expression of CCL24 (type 2) and higher expression of CCL5, CCL4 and CXCR3 (type 1) when compared with those with indeterminate form of disease. Together, these data reinforce a close-relation between T. cruzi genetic population and the host specific type 1 immune response and, for the first time, we show the distribution of type 1/2 chemokines associated with the development of cardiac pathology using dogs, a well similar model to study human Chagas disease.

Chemokines and chemokine receptors in arthritis

Chemokines are involved in leukocyte recruitment to inflammatory sites, such as the synovial tissue in rheumatoid arthritis (RA). There is a structural and a functional classification of chemokines. The former includes four groups: CXC, CC, C and CX3C chemokines. Chemokines may also be either inflammatory or homeostatic, however, these functions often overlap. Anti-chemokine and anti-chemokine receptor targeting may be therapeutically used in the future biological therapy of arthritis. Most data in this field have been obtained from animal models of arthritis as only very few human RA trials have been completed. However, it is very likely that various specific chemokine and chemokine receptor antagonists will be developed and administered to RA patients.

Chemokines – their role in immunotherapy for intraocular inflammation

Chemotactic cytokines are responsible for leukocyte migration and the immunopathogenesis of various inflammatory lesions. Together with other types of cytokines, chemokines play a major role in inducing/regulating inflammation and various immune responses. By targeting chemokines, immunotherapies could become another option for treating patients with uveitis. Indeed, a variety of chemokine-based therapies have been tested for their possible application for various pathological diseases, including intraocular inflammation. An example of chemokine-based therapy is anti-tumor necrosis factor (TNF)-alpha therapy, a very successful treatment. Chemokine- and cytokine-based therapies, therefore, appear to be a promising choice for the treatment of intraocular inflammation.

Mast cells and chemokines

Chemokines are small proteins (8-12 kD polypeptides) secreted by the cells of innate and adaptive immunity that mediate many of the functions of these cells, including recruitment of other cells. They are classified into families: CC, CXC and CX3C. CXC chemoattract mainly on neutrophils and CC act mainly on monocytes, eosinophils and mast cells. Mast cells are important cells in the modulation of allergic and inflammatory diseases. Activation of mast cells with specific IgE antibody and antigens or other active compounds such as Substance P and corticotrophin releasing hormone causes transcription and translation of several different cytokines/chemokines such as tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1 (MIP-1) and GM-CSF, RANTES, MCP-1, CXCL8, along with other proinflammatory compounds, proteases (chymase and tryptase), histamine, leukotrienes and prostaglandin D2. Neutralization of chemokines may reduce inflammatory cell accumulation and may protect against allergy, toxic shock syndrome and inflammatory diseases.

Role of chemokines in endocrine autoimmune diseases

Chemokines are a group of peptides of low molecular weight that induce the chemotaxis of different leukocyte subtypes. The major function of chemokines is the recruitment of leukocytes to inflammation sites, but they also play a role in tumoral growth, angiogenesis, and organ sclerosis. In the last few years, experimental evidence accumulated supporting the concept that interferon-gamma (IFN-gamma) inducible chemokines (CXCL9, CXCL10, and CXCL11) and their receptor, CXCR3, play an important role in the initial stage of autoimmune disorders involving endocrine glands. The fact that, after IFN-gamma stimulation, endocrine epithelial cells secrete CXCL10, which in turn recruits type 1 T helper lymphocytes expressing CXCR3 and secreting IFN-gamma, thus perpetuating autoimmune inflammation, strongly supports the concept that chemokines play an important role in endocrine autoimmunity. This article reviews the recent literature including basic science, animal models, and clinical studies, regarding the role of these chemokines in autoimmune endocrine diseases. The potential clinical applications of assaying the serum levels of CXCL10 and the value of such measurements are reviewed. Clinical studies addressing the issue of a role for serum CXCL10 measurement in Graves' disease, Graves' ophthalmopathy, chronic autoimmune thyroiditis, type 1 diabetes mellitus, and Addison's disease have been considered. The principal aim was to propose that chemokines, and in particular CXCL10, should no longer be considered as belonging exclusively to basic science, but rather should be used for providing new insights in the clinical management of patients with endocrine autoimmune diseases.

Quantification of chemokines by real-time reverse transcriptase PCR: applications in type 1 diabetes

Type 1 diabetes is a T-cell mediated autoimmune disease, characterized by the destruction of insulin-producing pancreatic beta-cells. This review will discuss the role of chemokines in the recruitment of immune cells leading to the pathology of this disease. There will be a focus on the quantification of chemokines and chemokine receptors by the recently developed real-time reverse transcriptase PCR technique. Today, this technique is in widespread use for analysis of chemokines in cells, tissues and tissue biopsies. The minute amount of tissue needed for analysis, as well as the very high sensitivity of this method, make it the method of choice for analysis of chemokines, which are often expressed at very low levels in target tissues. However, validation and optimization of the technique is of crucial importance for obtaining reliable results.

Les chimiokines : un réseau sophistiqué de guidage cellulaire

The immune system relies on the motility on various cell types that roam the host through the blood, the peripheral tissues and the lymphoid organs, looking for pathogens. Along their maturation and/or activation, the cell migratory capacities change in order to allow them to leave organs where they have been produced such as thymus and bone marrow, to locate in strategic sites to sense surrounding microbes, to meet and interact with other cells, and finally to access peripheral tissues and organs to eradicate the pathogens. This cell traffic is a highly organized process that involves numerous protein families such as adhesion molecules, proteases and chemotactic factors. Among the latter, chemokines are in the front line. We will here summarize the recent findings stressing out their physiopathological relevance and will describe thereafter their possible therapeutic use.

Structural correlates of antimicrobial efficacy in IL-8 and related human kinocidins

Chemokines are small (8-12 kDa) effector proteins that potentiate leukocyte chemonavigation. Beyond this role, certain chemokines have direct antimicrobial activity against human pathogenic organisms; such molecules are termed kinocidins. The current investigation was designed to explore the structure-activity basis for direct microbicidal activity of kinocidins. Amino acid sequence and 3-dimensional analyses demonstrated these molecules to contain iterations of the conserved gamma-core motif found in broad classes of classical antimicrobial peptides. Representative CXC, CC and C cysteine-motif-group kinocidins were tested for antimicrobial activity versus human pathogenic bacteria and fungi. Results demonstrate that these molecules exert direct antimicrobial activity in vitro, including antibacterial activity of native IL-8 and MCP-1, and microbicidal activity of native IL-8. To define molecular determinants governing its antimicrobial activities, the IL-8 gamma-core (IL-8gamma) and alpha-helical (IL-8alpha) motifs were compared to native IL-8 for antimicrobial efficacy in vitro. Microbicidal activity recapitulating that of native IL-8 localized to the autonomous IL-8alpha motif in vitro, and demonstrated durable microbicidal activity in human blood and blood matrices ex vivo. These results offer new insights into the modular architecture, context-related deployment and function, and evolution of host defense molecules containing gamma-core motifs and microbicidal helices associated with antimicrobial activity.

Chemokine receptors: attractive targets for drug discovery

Studies of two antibodies, efalizumab and natalizumab, have recently demonstrated that the blockade of leukocyte migration is of therapeutic benefit for the treatment of diseases such as psoriasis and multiple sclerosis. The role of chemokines in the control of cell traffic led to their receptors being considered one of the most promising family of targets aimed at disrupting cell recruitment in chronic inflammatory processes. Choosing the appropriate chemokine receptor for each disease was not easy, and the interpretation of target validation studies proved to be extremely difficult. Despite an intense effort in the search for chemokine receptor antagonists in the last decade, no compounds in advanced clinical trials exist as such. The inherent complexity of the family, the differences between the chemokine system in mice and men, and the species selectivity of small-molecule compounds could account for this fact. Pharmaceutical companies still believe in chemokine receptors as therapeutic targets, as demonstrated by the number of compounds reported to be in development. In the next years, the developmental progression of these compounds will reveal which target within the chemokine family is of real therapeutic value.

Chemokines as markers for parasite-induced inflammation and tumors

Chemokines are a group of small secreted proteins (8-10 kDa) produced and released by a wide variety of cell types. They were originally described as mediators of leukocyte recruitment, which is essential in acute and chronic inflammation. They also play a critical role in many pathophysiological processes such as allergic responses, infections and autoimmune diseases, tumor growth and hematopoietic development. This review introduces the three supergene families of chemokines (CXC, CC and C) with emphasis on their important role in different states in humans and in animal models with parasitic diseases. The concentration of transcription and translation of the cytokines and chemokines in the parasitic diseases may be an important marker for evaluation of the inflammatory state.

SMM-chemokines: a class of unnatural synthetic molecules as chemical probes of chemokine receptor biology and leads for therapeutic development

Chemokines and their receptors play important roles in numerous physiological and pathological processes. To develop natural chemokines into receptor probes and inhibitors of pathological processes, the lack of chemokine-receptor selectivity must be overcome. Here, we apply chemical synthesis and the concept of modular modifications to generate unnatural synthetically and modularly modified (SMM)-chemokines that have high receptor selectivity and affinity, and reduced toxicity. A proof of the concept was shown by transforming the nonselective viral macrophage inflammatory protein-II into new analogs with enhanced selectivity and potency for CXCR4 or CCR5, two principal coreceptors for human immunodeficiency virus (HIV)-1 entry. These new analogs provided insights into receptor binding and signaling mechanisms and acted as potent HIV-1 inhibitors. These results support the concept of SMM-chemokines for studying and controlling the function of other chemokine receptors.

Chemokines in host-parasite interactions in leishmaniasis

Crucial to the defense against leishmaniasis is the ability of the host to mount a cell-mediated immune response capable of controlling and/or eliminating the parasite. Cell recruitment to the site of infection is essential to the development of the host cellular immune response. The process is controlled by chemokines, which are chemotactic cytokines produced by leukocytes and tissue cells.

Engineering chemokines to develop optimized HIV inhibitors

Since the discovery that to enter target cells HIV uses receptors for the class of proteins known as chemokines, attempts have been made to generate anti-HIV molecules based on the chemokine ligands. A significant level of knowledge of the structure-activity relationships of chemokines has been amassed since the beginning of the 1990s. This, together with work that has elucidated the mechanisms underlying the inhibitory activity of chemokines, has guided not only the rational design of anti-HIV chemokine analogues, but also strategies by which chemokine variants with potent anti-HIV activity can be isolated from large libraries by phage display. This review summarizes the current knowledge about the structure-activity relationships and receptor biology of chemokines that is relevant to the development of analogues with anti-HIV activity. We present specific examples of engineered chemokine analogues with potent anti-HIV activity and describe the challenges that will need to be faced if these molecules are to be further developed for clinical applications. Finally, we discuss how these challenges might be met through further engineering of the molecules.

Chemokines in Myocardial Ischemia

Chemokine expression is markedly upregulated in healing myocardial infarcts and may play an important role in regulating leukocyte infiltration and activity and in modulating infarct angiogenesis as well as fibrous tissue deposition. The CC chemokine monocyte chemoattractant protein-1/CCL2 has important effects in infarct healing. Monocyte chemoattractant protein-1 -/- mice exhibit reduced macrophage infiltration and activation, suppressed cytokine synthesis, delayed phagocytotic removal of dead cardiomyocytes, diminished myofibroblast accumulation, and decreased ventricular remodeling after myocardial infarction. Monocyte chemoattractant protein-1 may also play an important role in the development of interstitial fibrosis in ischemic noninfarctive cardiomyopathy. CXC chemokines are also induced in healing infarcts. Interleukin-8/CXCL8 may mediate neutrophil recruitment and activation and may promote neovessel formation, whereas induction of the angiostatic and antifibrotic chemokine interferon-gamma-inducible protein-10/CXCL10 may serve to prevent premature wound angiogenesis and fibrous tissue deposition in the infarct, until the injured myocardium has been cleared from dead cells and debris and a fibrin-rich provisional matrix is formed. Understanding of the role of chemokines in myocardial ischemia may result in novel strategies in the treatment of patients with ischemic heart disease.

Inflammation and autoimmunity as a central theme in neurodegenerative disorders: fact or fiction?

Irrespective of the initiating stimuli, neurodegenerative disorders including multiple sclerosis (MS), Alzheimer's disease, Parkinson's disease and stroke share many characteristics of inflammation and autoimmunity. This review summarizes and correlates the information relating to the role of cytokines and chemokines in initiating and propagating the inflammatory/immune response in these pathologies. For example, in MS there is a continuous realignment in the inflammatory and immune response. However, due to the redundancy in the cytokine/chemokine response, it is extremely unlikely that any one therapy will be successful in treating neurodegenerative diseases. This review attempts to highlight specific targets for therapeutic intervention.

Chemokines: multiple levels of leukocyte migration control

The surge in interest in chemokines is explained by the recognition that numerous aspects of immunity are intimately related to leukocyte traffic. Chemokines are leukocyte attractants but also contribute to immune processes that do not directly involve leukocyte migration. Recent progress is most evident in the areas of lymphocyte development, immune response initiation and immune pathology. Important observations have also been reported on chemokine-receptor interactions, signal transduction and cellular responses. New insights into the role of chemokines in leukocyte attraction and relocation will be discussed, with emphasis on the distinct levels of leukocyte migration control that ultimately determine the performance of our immune defense system.

Chemokines

Chemokines are small proteins that control cellular migration. An extensive family of these molecules has been described in mammals containing nearly 50 members. Within this family are four groups, each defined by the different spacing of two N-terminal cysteines, which form disulphide bonds with two other cysteine residues to create the tertiary structure characteristic of chemokines. Recent evidence shows the chemokine family is not unique to mammals, with several members also identified in birds, amphibians and fish, including a primitive vertebrate, the lamprey. Although there is less evidence to define the roles of chemokines in these lower vertebrates, structural similarities allow some predictions to their function, against which further studies are being made. Additionally, some microorganisms (particularly viruses) appear to have copied genes for chemokines, presumably to confuse the immune system of their host. This review aims to bring together the current information concerning identified chemokines throughout vertebrates and microorganisms.

Chemokines in the corpus luteum: implications of leukocyte chemotaxis

Chemokines are small molecular weight peptides responsible for adhesion, activation, and recruitment of leukocytes into tissues. Leukocytes are thought to influence follicular atresia, ovulation, and luteal function. Many studies in recent years have focused attention on the characterization of leukocyte populations within the ovary, the importance of leukocyte-ovarian cell interactions, and more recently, the mechanisms of ovarian leukocyte recruitment. Information about the role of chemokines and leukocyte trafficking (chemotaxis) during ovarian function is important to understanding paracrine-autocrine relationships shared between reproductive and immune systems. Recent advances regarding chemokine expression and leukocyte accumulation within the ovulatory follicle and the corpus luteum are the subject of this mini-review.

TGFbeta inhibits LPS-induced chemokine mRNA stabilization

The mechanisms involved in anti-inflammatory action of transforming growth factor beta (TGFbeta) have been examined by evaluating its effect on chemokine gene expression in mouse macrophages. Lipopolysaccharide (LPS)-stimulated expression of the CXC chemokines KC and MIP-2 was selectively reduced by TGFbeta in a time- and protein synthesis-dependent process. While TGFbeta had a modest effect on transcription of the KC and MIP-2 mRNAs as measured by nuclear run-on, it had no effect on LPS-stimulated luciferase expression driven by the KC promoter nor on the activation of nuclear factor kappaB (NFkappaB) DNA-binding activity and transactivation function. Interestingly, KC mRNA levels were markedly reduced by TGFbeta treatment in cells transfected with KC genomic or cDNA constructs driven from either the KC or cytomegalovirus (CMV) promoters, demonstrating the importance of sequences within the mature mRNA and suggesting that suppression may involve a posttranscriptional mechanism. In support of this possibility, LPS stimulation prolonged the half-life of KC mRNA and this stabilization response was blocked in cells treated with TGFbeta. Examination of KC mRNA expressed under control of a tetracycline-responsive promoter demonstrated that TGFbeta prevented stabilization of KC mRNA, in response to LPS but did not alter KC mRNA half-life directly. KC mRNA stabilization by LPS was dependent on activation of p38 mitogen-activated protein kinase (MAPK) activity, and TGFbeta treatment inhibited p38 MAPK activation. These findings support the hypothesis that TGFbeta-mediated suppression of chemokine gene expression involves antagonism of LPS-stimulated KC mRNA stabilization via inhibition of p38 MAPK.

High glucose-induced expression of proinflammatory cytokine and chemokine genes in monocytic cells

Monocyte activation and adhesion to the endothelium play important roles in inflammatory and cardiovascular diseases. These processes are further aggravated by hyperglycemia, leading to cardiovascular complications in diabetes. We have previously shown that high glucose (HG) treatment activates monocytes and induces the expression of tumor necrosis factor (TNF)-alpha via oxidant stress and nuclear factor-kB transcription factor. To determine the effects of HG on the expression of other inflammatory genes, in the present study, HG-induced gene profiling was performed in THP-1 monocytes using cytokine gene arrays containing 375 known genes. HG treatment upregulated the expression of 41 genes and downregulated 15 genes that included chemokines, cytokines, chemokines receptors, adhesion molecules, and integrins. RT-PCR analysis further confirmed that HG significantly increased the expression of monocyte chemoattractant protein-1 (MCP-1), TNF-alpha, beta(2)-integrin, interleukin-1beta, and others. HG treatment increased transcription of the MCP-1 gene, MCP-1 protein levels, and adhesion of THP-1 cells to endothelial cells. HG-induced MCP-1 mRNA expression and monocyte adhesion were blocked by specific inhibitors of oxidant stress, protein kinase C, ERK1/2, and p38 mitogen-activated protein kinases. These results show for the first time that multiple inflammatory cytokines and chemokines relevant to the pathogenesis of diabetes complications are induced by HG via key signaling pathways.

Chemokines and breast cancer: a gateway to revolutionary targeted cancer treatments?

Breast cancer is an example of a solid tumour which is well treated in the early stages of disease by surgical excision, but once metastatic spread has occurred, medical therapies (chemotherapy and radiotherapy) are highly toxic, expensive and palliative. It is known that certain tumours exhibit specific patterns of metastasis, chemokines may provide a molecular answer to this mystery. Chemokines and their receptors play important roles in the various stages of tumour development and metastasis. Chemokines interact with their specific receptors as well as interacting with the glycosaminoglycan (GAG) component of proteoglycan. We discuss the basic metastatic process and the involvement of chemokines in breast cancer biology. Finally, we summarize potential therapeutic applications of chemokines and chemokine/glycosaminoglycan interactions including chemokine agonists, antagonists, anti-sense therapy, immunotherapy and soluble GAGs, as well as future perspectives in this field.

Regulation of T cell migration during viral infection: role of adhesion molecules and chemokines

T cell mediated immunity and in particular CD8+ T cells are pivotal for the control of most viral infections. T cells exclusively exert their antiviral effect through close cellular interaction with relevant virus-infected target cells in vivo. It is therefore imperative that efficient mechanisms exist, which will rapidly direct newly generated effector T cells to sites of viral replication. In the present report we have reviewed our present knowledge concerning the molecular interactions, which are important in targeting of effector CD8+ T cells to sites of viral infection.

[Chemokines and tumors]

Chemokines are cytokines which induce chemotaxis on many cell types, thus regulating cell migration within inflammatory and allergic sites, and leucocyte homing. Also, they play a crucial role in inflammatory and tumor-associated angiogenesis, as well as in tumor progression. Chemokines are grouped into: 1) alpha or CXC; 2) beta or CC; 3) gamma or C; 4) delta or CX3C molecules. Each of them recognizes one or more cell surface receptors, named CXCR, CCR, XCR, CX3CR respectively, according to the corresponding subfamily. Many chemokines have been identified within tumor tissues, as a secretory product of tumor cells and/or inflammatory cells. The CXC chemokines (such as IL-8, IP10, Mig, SDF-1 alpha) or CC chemokines (such as MCP-1, MIP-1 alpha, eotaxin, RANTES) have been frequently harvested from tumor tissues or the biological fluids of patients. Some chemokines inhibit tumor growth and progression by activating immunocompetent cytolytic cells or inhibiting tumor-associated angiogenesis. In contrast, other chemokines induce tumor progression by interacting with the specific receptor expressed on the tumor cells and hence by activating chemotaxis and secretion of proteolytic enzymes, or by inducing angiogenesis and metastatic spreading. Sometimes neoplastic cells express chemokine receptors which are not expressed on their normal counterpart. Data from this lab show the CXCR3 expression by cells from lymphoproliferative diseases, such as multiple myeloma and lymphoma, and the stimulation of an invasive phenotype following interaction with specific chemokines.

Legionella pneumophila pathogenesis and immunity

Legionella pneumophila is a ubiquitous intracellular bacterium found widely in the environment and is the cause of sporadic outbursts of opportunistic infection, mainly in immunocompromised individuals, including young children as well as aged persons. The host response to this organism is similar to responses to other opportunistic intracellular microbes and features both innate and adoptive immune mechanisms. Innate immunity includes the responses of a variety of host cells and cytokines, including those produced by macrophages stimulated by microbial antigens. Adoptive immunity consists of activated lymphocytes and the cytokines they produce, such as interferon and other cytokines that activate macrophages to restrict the growth and spread of intracellular bacteria. The role of cytokines specifically in resistance and immunity to Legionella is exemplified by studies concerning the nature and mechanism whereby interferon produced by activated T lymphocytes influences macrophages to resist infection by this bacterium, not only by restricting growth but also killing this bacterium. This cytokine is considered to have a key role in activating macrophages in adoptive immunity to Legionella and other intracellular bacteria. In particular, interferon is known to have a crucial role in activating macrophages to resist infection by L. pneumophila. This review also describes newer findings that demonstrate that various cytokines that define Th1 vs Th2 helper cell activity also are important in regulating resistance versus susceptibility to this ubiquitous microorganism.

Chemokines and dendritic cells: a crucial alliance

Dendritic cells (DC) are bone marrow-derived professional antigen-presenting cells that function as sentinels of the immune system. Their importance in immunity resides in their unique ability to prime or tolerize T lymphocytes, thereby initiating or inhibiting immune responses. They reside in all tissues and organs and upon appropriate activation, migrate to secondary lymphoid organs to present antigen to T lymphocytes in the T cell zones. Because of this central role in T cell activation, there is a great deal of interest in using DC therapeutically to deliver positive or negative signals to the immune system. The DC system is critically dependent on the ability of DC at different stages of maturation to respond to a range of soluble and cell-bound signals, including members of the chemokine gene superfamily. This review will describe the interactions between DC and the chemokine system.

Characterization of chemokines and their receptors in the central nervous system: physiopathological implications

Chemokines represent key factors in the outburst of the immune response, by activating and directing the leukocyte traffic, both in lymphopoiesis and in immune surveillance. Neurobiologists took little interest in chemokines for many years, until their link to acquired immune deficiency syndrome-associated dementia became established, and thus their importance in this field has been neglected. Nevertheless, the body of data on their expression and role in the CNS has grown in the past few years, along with a new vision of brain as an immunologically competent and active organ. A large number of chemokines and chemokine receptors are expressed in neurons, astrocytes, microglia and oligodendrocytes, either constitutively or induced by inflammatory mediators. They are involved in many neuropathological processes in which an inflammatory state persists, as well as in brain tumor progression and metastasis. Moreover, there is evidence for a crucial role of CNS chemokines under physiological conditions, similar to well known functions in the immune system, such as proliferation and developmental patterning, but also peculiar to the CNS, such as regulation of neural transmission, plasticity and survival.

Molecular cloning and sequencing of 25 different rhesus macaque chemokine cDNAs reveals evolutionary conservation among C, CC, CXC, AND CX3C families of chemokines

Chemokines are small chemoattractant cytokines involved in normal and pathological immune processes. Although extensive nucleotide sequence data are available for human and murine chemokine cDNA sequences, very few data are currently available regarding rhesus macaque sequences. To increase our understanding of immune function in nonhuman primates, we have used reverse-transcription polymerase chain reaction (RT-PCR) to clone and sequence rhesus macaque cDNAs from each of the C, CC, CXC, and CX3C groups of chemokines. Relative to the respective human chemokines, these 25 chemokine cDNA sequences were from 77% to 98% identical. Of the amino acid differences between the rhesus macaque and human chemokines, 51% were species-specific when compared together with the respective murine chemokine sequences. These studies of rhesus macaque chemokine sequences demonstrate that chemokine genes are highly conserved across species, and provide a large foundation for the study of chemokine biology and genetics in nonhuman primates.

Uterine chemokines in reproductive physiology and pathology

PROBLEM

Chemokines are increasingly recognized as important regulators of uterine function.

METHODS OF STUDY

The following is a review of uterine chemokines, especially monocyte chemotactic protein (MCP)-1, interleukin (IL)-8, and regulated-upon-activation normal-T-cell-expressed and -secreted (RANTES) protein, in reproductive physiology and pathology.

RESULTS

It is increasingly clear that IL-8, MCP-1, RANTES and their receptors are produced by endometrial, myometrial, and trophoblast cell types in a timed and co-ordinated manner. In addition to the regulation of leukocyte migration and function, uterine chemokines also display specific roles in endometrial angiogenesis, apoptosis, proliferation, and differentiation. IL-8, MCP-1 and RANTES are regulated by local growth factors and cytokines such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma, and IL-1. IL-8 takes part in cervical ripening and parturition. IL-8, MCP-1 and RANTES are also found at high levels in the peritoneal fluid of women with endometriosis.

CONCLUSION

Co-ordination of chemokine-chemokine receptor interactions plays an important role in the menstrual cycle and successful pregnancy. Moreover, unbalanced chemokine expression contributes to pathologic conditions typified by uncontrolled cellular proliferation, migration and invasion.

Chemokines in immunity

Chemokines are a superfamily of small, heparin-binding cytokines that induce directed migration of various types of leukocytes through interactions with a group of seven-transmembrane G protein-coupled receptors. At present, over 40 members have been identified in humans. Until a few years ago, chemokines were mainly known as potent attractants for leukocytes such as neutrophils and monocytes, and were thus mostly regarded as the mediators of acute and chronic inflammatory responses. They had highly complex ligand-receptor relationships and their genes were regularly mapped on chromosomes 4 and 17 in humans. Recently, novel chemokines have been identified in rapid succession, mostly through application of bioinformatics on expressed sequence tag databases. A number of surprises have followed the identification of novel chemokines. They are constitutively expressed in lymphoid and other tissues with individually characteristic patterns. Most of them turned out to be highly specific for lymphocytes and dendritic cells. They have much simpler ligand-receptor relationships, and their genes are mapped to chromosomal loci different from the traditional chemokine gene clusters. Thus, the emerging chemokines are functionally and genetically quite different from the classical "inflammatory chemokines" and may be classified as "immune (system) chemokines" because of their profound importance in the genesis, homeostasis and function of the immune system. The emergence of immune chemokines has brought about a great deal of impact on the current immunological research, leading us to a better understanding on the fine traffic regulation of lymphocytes and dendritic cells. The immune chemokines and their receptors are also likely to be important future targets for therapeutic intervention of our immune responses.

[Chemokines and defense-system cell homing]

The general properties of chemokines and their receptors are described, and the perspectives raised for cellular therapy are discussed. Specific examples are provided in the cases of the CXC chemokine SDF1 and of chemokines ligands of CCR5.

Chemokines and innate immunity

Our environment contains a great variety of infectious microbes that may be potentially destructive and threaten our survival. As soon as microbes try to establish a site of infection, the host launches a complex defense system. Innate immunity is a non-specific response and serves as the first-line of defense where phagocytes, such as neutrophils and macrophages, and NK cells play central roles in neutralizing and clearing microorganisms. Thus, migration of cells into infectious foci and subsequent activation of these cells appear to be a critical step, enabling the host to achieve effective and efficient removal of microbes. Over the past decade, chemokines have been identified as chemotactic cytokines that attract and activate specific types of leukocyte populations in vitro. There is now evidence that the magnitude of chemokines' expression in infectious diseases is strongly associated with the severity of the inflammatory responses. Blocking chemokines or their receptors with neutralizing antibodies or gene targeting technology has allowed us to understand the pathological significance of chemokines in animal models of infectious diseases. Growing evidence suggests that chemokines play an important beneficial role in immune system development, homeostasis and in innate immunity, which may pave the way for new therapeutic strategies for the treatment of infectious diseases.

Chemokines in cutaneous wound healing

Healing of wounds is one of the most complex biological events after birth as a result of the interplay of different tissue structures and a large number of resident and infiltrating cell types. The latter are mainly constituted by leukocyte subsets (neutrophils, macrophages, mast cells, and lymphocytes), which sequentially infiltrate the wound site and serve as immunological effector cells but also as sources of inflammatory and growth-promoting cytokines. Recent data demonstrate that recruitment of leukocyte subtypes is tightly regulated by chemokines. Moreover, the presence of chemokine receptors on resident cells (e.g., keratinocytes, endothelial cells) indicates that chemokines also contribute to the regulation of epithelialization, tissue remodeling, and angiogenesis. Thus, chemokines are in an exclusive position to integrate inflammatory events and reparative processes and are important modulators of human-skin wound healing. This review will focus preferentially on the role of chemokines during skin wound healing and intends to provide an update on the multiple functions of individual chemokines during the phases of wound repair.

Chemokines, chemokine receptors and allergy

Chemokines are a group of cytokines that are responsible for the influx of blood cells, including T and B lymphocytes, monocytes, neutrophils, eosinophils and basophils, in allergic and other inflammatory conditions. They function as G protein-coupled chemotactic factors which also activate the cells with which they interact. Certain chemokines function within the afferent arm of the immune system, in which antigen is processed and antibody formation initiated, and others are active within the effector pathways of cellular immunity and late-phase allergic reactions. Th2 lymphocytes, which are critical for allergy, employ the CC chemokine receptors CCR4 and CCR8 with the ligands thymus- and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and I-309, respectively. The chemokine receptor CCR3 and ligands monocyte chemoattractant protein (MCP)-3, MCP-4, regulated upon activation normal T cell expressed and secreted (RANTES) and eotaxins I and II are of particular relevance for the recruitment and activation of eosinophils. Th1 reactions depend upon interferon gamma-induced CXC chemokines interferon- inducible protein (IP)-10, interferon-inducible T cell-alpha chemoattractant (iTAC) and monokine induced by interferon-gamma (MiG), which bind to chemokine receptor CXCR3.

[Chemokines and chemokine receptors. Review article]

Chemokines form a new superfamily of small glycoproteins. They are key molecules that activate and direct the migration of different types of leukocytes from the blood stream into sites of infection and inflammation. In addition to this role certain chemokines have been reported to act on different types of cells (e.g. hematopoietic progenitor cells, dendritic cells, fibroblasts, keratinocytes). Other of them also play a role in wound healing, in angiogenesis and in viral infections. These molecules have a high degree of amino acid sequence homology and they have four conserved cysteins forming two essential disulphide bonds. They are divided into four classes (families) depending on the position of the first two cystein residues. Chemokines mediate their proinflammatory effects by binding to a variety of specific receptors, belonging to the G protein-coupled superfamily of seven-transmembrane (serpentine) receptors. Some of this receptors serve as coreceptors for HIV-viruses, some of them could be expressed as markers preferentially in Th1 or Th2 subpopulations. This paper summarizes data on chemokines and their receptors, target cells and production in physiological and pathological conditions.

Chemokines as mediators of diseases related to surgical conditions

Chemokines are important mediators of inflammation. Animal studies suggest that inhibition of chemokine action results in a decrease in inflammation. Novel anti-inflammatory agents directed against chemokines are now available. Surgeons are uniquely positioned to treat multiple chemokine-mediated diseases. In this article, we review the biology and nomenclature of chemokines as well as their role in neutrophil migration. Further, the potential role of chemokines in various diseases related to surgical conditions, including adult respiratory distress syndrome, atherosclerosis, inflammatory bowel disease, and solid organ rejection, is reviewed. Finally, the idea that chemokines could be targets for novel therapeutic agents is discussed.

Chemokines, chemokine receptors, and renal disease: from basic science to pathophysiologic and therapeutic studies

Leukocyte trafficking from peripheral blood into affected tissues is an essential component of the inflammatory reaction to virtually all forms of injury and is an important factor in the development of many kidney diseases. Advances in the past few years have highlighted the central role of a family of chemotactic cytokines called chemokines in this process. Chemokines help to control the selective migration and activation of inflammatory cells into injured renal tissue. Chemokines and their receptors are expressed by intrinsic renal cells as well as by infiltrating cells during renal inflammation. This study summarizes the in vitro and in vivo data on chemokines and chemokine receptors in renal diseases with a special focus on potential therapeutic effects on inflammatory processes.

The role of chemokines in the immunopathology of pulmonary disease

During the last decade, our understanding of the mechanisms involved in the initiation and maintenance of pulmonary disease has been greatly aided by advances in the field of chemokine biology. Chemokines comprise four supergene families, two of these families (the CC and CXC chemokine groups) are quite large and contain over 50 identified ligands and at least 14 individual receptors. Two additional chemokine families (C, CXXXC chemokines) are small and contain lymphotactin and fractalkine, respectively, as their members. In addition to their originally identified chemotactic activity, chemokines possess a variety of biological activities, ranging from immunomodulating leukocyte activation to suppressing HIV infection. The latter effect is due to the ability of specific chemokine receptors to serve as co-receptor for HIV entry into specific leukocyte sub-populations. A number of in vitro and in vivo studies have underscored the importance of chemokine biology in the progression of both acute and chronic lung diseases. These investigations have demonstrated the importance of targeting chemokines for new therapeutic approaches to treat pulmonary disease. A variety of acute and chronic lung diseases have been shown to possess a chemokine component and contribute to the initiation and maintenance of lung pathology, thus, there is little doubt that a further understanding of the mechanisms of pulmonary diseases will rely upon advances in the field of chemokine biology.

Chemokines and allergic disease

Understanding the chemokine network has become one of the great challenges for researchers interested in inflammatory mechanisms and inflammation-based diseases. The complexity and diversity of the system provide not only a daunting task for its comprehension but also numerous opportunities for development of new, targeted therapies. It is now certain that chemokines are involved as important mediators of allergic inflammation; the fine details and scope of their roles are now under investigation. Presumably, because of distinct pressures on the immune systems of people living in different geographic regions, genetic variation of ligands, receptors, and regulatory regions in the network have emerged. Establishing the roles of these polymorphisms in determining disease susceptibility or progression among individuals and in distinct ethnic groups will provide a basis for improved understanding and treatment of allergic diseases.

Chemokines in inflammatory states

Chemokines probably mediate inflammation in asthma by acting on endothelial cells, alveolar cells, neutrophils, eosinophils, basophils, mast cells, monocytes, and lymphocytes, which are inhibited by corticosteroids. In 1995, we found that MCP-1 provokes mast cell aggregation and [3H]5HT-release in cultured mast cells. In another study, MCP-1 and RANTES revealed to have a potent chemoattractive effect on basophilic cells originating from the rat skin. In this inflammatory model, RANTES also attracted eosinophils and macrophages along with basophilic cells. The effect of RANTES on inducing HDC mRNA was dose dependent. MCP-1 and RANTES provoked histamine release in intradermal mast cells and prostaglandin D2 generation. These effects clearly show that RANTES and MCP-1 are mediators of acute inflammatory responses. In chronic inflammatory reactions, MCP-1 is also present as we show in a study recently published by our group. In this paper, we found that MCP-1, strongly mediates the recruitment of mononuclear cells in the granuloma formed by KMnO4. In addition, MCP-1 mediated a parasitic infection caused by Trichinella spiralis in mice. Our data strongly demonstrate that chemokines, such as RANTES and MCP-1, mediate acute inflammatory response.