This review describes the role of the nuclear hormone receptor PPARgamma as a double-edged sword in sepsis. On the one hand, PPARgamma inhibits pro-inflammatory gene expression, predominantly by scavenging transcription factors and their cofactors, thus preventing them from binding to their cognate binding sites in the promoters of target genes. The expressions of the affected genes, such as those for inducible nitric oxide synthase, TNF-alpha, or IL-1beta are repressed. Therefore, PPARgamma is suggested to be beneficial in hyper-inflammatory diseases, such as sepsis. In n animal models of sepsis, PPARgamma agonist pretreatment auspiciously attenuated inflammation compared with control animals, accompanied by their improved survival rate. On the other hand, PPARgamma provokes apoptosis, which in the hyper-inflammatory phase of sepsis might be helpful because the number of immune cells, such as monocytes, macrophages, and neutrophils, involved in secreting high amounts of pro-inflammatory mediators will be reduced. In contrast, during the anti-inflammatory phase, cell death of immune cells, especially of T lymphocytes, is supposed to be deleterious. Under these circumstances, a second infection cannot be adequately answered, thus causing septic shock and multi-organ dysfunction syndrome. Therefore the role of PPARgamma is still ambiguous. Particularly its role in initiating apoptosis awaits further clarification to finally elucidate its impact on sepsis development.
The CD3 zeta chain, a component of the T cell receptor (TCR)/CD3 complex, is considered to be a limiting factor in the assembly and transport of the TCR/CD3 complex to the cell surface and is crucial to receptor signaling function. Recent studies have demonstrated altered expression and function of this signal transduction molecule in T and natural killer cells in patients with chronic inflammatory/autoimmune diseases. In this review, current knowledge concerning the expression of CD3 zeta chain as well as the mechanisms responsible for abnormal expression of this molecule in systemic lupus erythematosus, rheumatoid arthritis, and childhood idiopathic nephrotic syndrome are summarized.
The etiology and pathogenesis of inflammatory bowel disease (IBD) remains unsolved but improved experimental models of enterocolitis have led to progress. Intestinal inflammation can be induced by chemical or dietary factors or by microbial products and experimental IBD. Many animal models of IBD can be used to evaluate new anti-inflammatory drugs. These models, however, usually demonstrate acute, self-limiting colitis. The spontaneous colitis models developed in the monkey, cotton-top tamarin, and C3H/HeJBir mouse mimic more features of human IBD. Inflammation is chronic and is under genetic control. The differential genetic susceptibility of inbred rat strains to chronic inflammation have been exploited. Lewis rats injected with bacterial products, peptidoglycan polysaccharide or indomethicin develop chronic relapsing enterocolitis, whereas closely related Buffalo or Fisher rat strains develop only transient inflammation and the specific inhibition of inflammatory mediators and target molecules have been tested. Over-expression (transgenic) or deletion (knockout) of specific genes have led to the development of rodent models of spontaneous colitis. Inflammation arises from a number of mutations of immunomodulatory molecules supporting the concept of genetic heterogeneity for IBD. The results obtained from experimental models have generated new hypotheses, expanded human studies, and suggested novel forms of therapy for IBD patients.
Introduction: Endotoxemia developing during cardiosurgery as elevated endotoxin concentrations in patient's serum may prevail over 24 h after operation. A major reason is thought to be increased gut permeability resulting in endotoxin and bacterial leakage. In this study we aimed to measure endotoxin levels on samples obtained during and after cardiovascular procedures and compare them with clinical observations and laboratory test results. Materials and Methods: 3-Hydroxy fatty acids (3-OH FAs) of 10?18 carbon chain length, chemical markers of endotoxin (lipopolysaccharide), were determined in patient sera by gas chromatography-mass spectrometry-based analysis. Results were compared with routine laboratory tests: blood morphology, urine, ALT, AST, bilirubin, kidney parameters, clotting parameters, and gasometry. Results: Of a total of 16 patients, 5 patients (group I) showed increased serum 3-OH FA levels and 11 patients (group II) did not show any change in 3-OH FA levels 24 h after operation. All group I patients revealed leukocytosis, two developed post-operative anemia. Significantly different changes were observed: the initial, pre-operative 3-OH FA levels were similar for both groups, while group I patients showed increased levels of all the studied 3-OH FAs during the operation (p0.05), and 3-OH C14 and 3-OH C16 remained elevated 24 h after the operation. Conclusions: Cardiosurgery may strongly promote gut endotoxin translocation to the blood in some patients. Prolonged leukocytosis, deep anemia, and increased liver dysfunction markers may indicate the need for observation of possible endotoxemia development. It is recommended to monitor the endotoxin level and/or endotoxemia markers in cardiosurgery patients.
Angiogenesis is essential for tumor progression, growth and metastases. Many substances present in a normal organism can inhibit or stimulate the process of new vessel formation in tumors. The use of natural or synthetic angiogenesis inhibitors as anticancer drugs is currently under intense investigation. Such agents can have lower toxicity and are less likely to generate drug resistance than conventional cytotoxic drugs. Clinical trials are now underway to develop optimum treatment strategies for antiangiogenic drugs. This paper reviews the present achievements in preclinical and clinical studies with antitumor drugs based on inhibitors of angiogenesis.
Neural cell adhesion molecules (NCAM) play an important role in embryogenesis and in some tumors, especially of neuroectodermal origin. In this study, eighteen cases of invasive breast carcinoma, seven cases of sigmoid colon carcinomas and seventeen cases of the non-small cell lung carcinoma were immunostained for NCAM. The NCAM expression, usually focal, was observed in some cases only. NCAM was expressed in the membranes, in a fine granular pattern. In three cases of breast cancers, also cytoplasmic localisation of NCAM was observed, which may suggest its cytoplasmic formation. Furthermore, in three cases expression of NCAM in histologically normal ductal lobular units adjacent to invasive breast cancers without presence of this antigen in cancer tissue was observed. The immunostaining was weak or absent in sigmoid colon carcinomas. In this study we confirm observation of some authors that NCAM expression occurs in some cases of non-small cell lung carcinomas.
The successful use of hepatocytes depends on a reliable demonstration of the functional and morphological integrity of isolated cells. Herein we investigated whether the isolation and cryopreservation of primary human hepatocytes can compromise cell viability and liver-specific characteristics. Hepatocytes were isolated from encapsulated human liver segments by a modified 2-step perfusion technique. Isolated cells were Percoll-purified, cryopreserved, and stored in liquid nitrogen for 1?12 months. For rapid assessment of fresh and cryopreserve/thawed hepatocyte yield and viability, the cells were stained with trypan blue or labeled with fluorochromes. For immunocytochemical analysis, the cells were labeled with monoclonal antibodies for the presence of the following antigens and chemokines: CD3, CD45Ro, CD45Ra, CD34, CD68, CD90, CD95, CD20, HLA-DR, Ki67, PCNA, Bcl-2, p53, CXCR3, CXCR4, and SDF-1. The cells were tested for several specific functions, such as ureagenesis, energy status, MTT activity, lactate dehydrogenase leakage, and total CYP450 content. Assessment of both freshly isolated (Percoll-purified) and cryopreserved/thawed hepatocytes revealed a low constitutive level of contamination by non-parenchymal cells compared with crude (unpurified) preparations and tissue sections. All viable hepatocytes showed intact morphology and retained CYP450 protein, energy status, and urea synthesis. Modifications in hepatocyte preparations, such as depletion of dead, damaged, and non-parenchymal cells, improves cell purity, which can be adapted to further evaluation of hepatocyte immunogenicity. These data illustrate the importance and feasibility of human hepatocyte banking.
The generation of an effective immune response involves antigen-specific T cell expansion and differentiation of effector function. T cell activation requires at least two distinct signals, including signaling via the Ag-specific TCR and a costimulatory pathway. Antigen stimulation of T cells can lead either to a productive immune response characterized by proliferation, differentiation, clonal expansion and effector function or, in absence of appropriate costimulation, to a state of long-lasting unresponsiveness termed anergy. Anergic T cells fail to proliferate and secrete cytokines in response to secondary stimulation. The interaction between costimulatory molecule CD28 on T cells with members of the B7 family on APC results in upregulation of T cell proliferation, cytokine production and induces the expression of the anti-apoptotic protein Bcl-xl. Based of those findings, the two-signal requirement model for T cell activation is today generally accepted. The negative regulatory mechanisms during T cell activation are not well understood, but they are crucial for the maintainance of lymphocyte homeostasis. For several years the functional role of the enigmatic CD28 homologue CTLA-4 (cytotoxic T lymphocyte antigen-4) in T cell activation has been both obscure and conteroversional. CTLA-4 was initially proposed to provide a costimulatory signal in conjunction with TCR/CD3 signaling. Today we know that CD28 and CTLA-4 molecules may have diametrically opposed functions: signaling via CD28, in conjunctive with TCR, is required for T cell activation, while signaling via CTLA-4 is a negative signal that inhibits T cell proliferation. How the T cell integrates signals through the TCR/CD3 complex, CD28 and CTLA-4 to initiate, maintain and terminate antigen-specific immune response is actually not fully clarified. In this review, we will focus on the emerging role of CTLA-4 as a negative regulator of T lymphocyte activation and its role in dynamic interplay of activatory and inhibitory signals.
The complexity of biological systems, and the explosion of the quantity of biological information which is rapidly becoming available from experimental and clinical studies, necessitate the use of theoretical tools, namely, mathematical and computational modeling. The vertebrate adaptive immune system, with its learning and memory capabilities, is a particularly rich source of modeling challenges. Most difficult within this area is the study of lymphocyte repertoires ? the generation of their diversity and the forces that shape the ever-changing dynamics of lymphocyte clones. I review several examples of problems in lymphocyte repertoire modeling, demonstrate the types of solutions employed, and highlight the contribution of these theoretical studies to immunological research.
Vascular endothelial growth factor (VEGF) is an angiogenic cytokine with potential therapeutic applications in human diseases. It is a mitogen primarily for endothelial cells. The transfer of the cDNA encoding VEGF to ischemic tissues, which cannot be revascularized otherwise, represents a novel and promising approach to the treatment of vascular disorders. In this work the VEGF165 cDNA was cloned into the expression vector pSecTag2B. The activity of the construct was studied in cell culture as well as in vivo. Western blotting study showed that the cells transfected with the vector secreted significantly higher amounts of VEGF to the culture medium than the non-transfected cells. In vivo study revealed an increased number of new vessels in animals injected with vector encoding VEGF as compared with empty plasmid. Also, tumor cells transfected with the VEGF plasmid exhibited extensive vascularization.
The motility of perpheral blood mononuclear cells (MNC) and polymorphoxnuclear (PMN) leukocytes form normal and bee venom allergic subjects was investigated by a modified Boyden micropore filter method. The study comprised MNC locomotion in bee venom and gradients and PMN locomotion in bee venom and fMLP gradients. We demonstrated statistically significant increase in MNC and PMN motility towards bee venom in allergic patients group. This effect disappeared after the preincubation of MNC with anti-human IgE antiboidies. We observed no such effect in PMN leukocytes. Increased MNC motility in histamine gradient was observed only in control subjects group. Similarily significant increase in PMN locomotion towards fMLP was found in both allergic and control subjects. The results here demonstrated suggest that a specific allergen might be a chemoattractant for peripheral blood MNC and PMN leukocytes from atopics and could be capable to induce non-infectious inflammatory reactions as a result of its interaction with these sensitive cells.
The systemic inflammatory response reflects the non-specific clinical expression of a profound activation of the body?s immune responsive elements. Immune activation and immune suppression coexist in the blood of patients with severe sepsis. It is their interaction and the resultant host parenchymal responses that ultimately define the course of sepsis. Importantly, neither profound immune activation (pro-inflammatory) or immune suppression (anti-inflammatory) characterize the dominant process. Rather, there is a combined low grade pro-inflammatory state associated with an immune hyporesponsiveness that defines the usual immunologic state of the patient with severe sepsis.
Corticotropin-releasing factor (CRF) was originally identified as a hypothalamic peptide which stimulates secretion of the hypophyseal adrenocorticotropic hormone. CRF exhibits its actions through G protein-dependent seven-membrane-domain receptors. Two subtypes of CRF receptors (CRFR1 and CRFR2) have been characterized thus far. CRF and its receptors were found in a number of brain regions, where they function by neuromodulation, and also in several peripheral organs. Besides CRF, another naturally occurring CRF-like peptide, urocortin, has been characterized. In the immune system, CRF and CRFR1 have so far been detected at both mRNA and protein lelvels in several lymphoid organs and at sites of inflammation. Locally injected CRF was shown to modulate the severity of inflammation. This effect was not only a result of hemodynamic changes known to be induced by CRF or by activation of the hypothalamo-pituitary adrenal axis, as CRF-binding sites were also found on immune cells. CRF was shown to directly modulate secretion of cytokines and neuropeptides, proliferation, chemotaxis and degranulation of purified macrophage and lymphocyte populations in vitro . The presence of functional CRFR was more recently demonstrated also on polymorphonuclear cells and significant amounts of CRF were shown to be produced in lymphoid organs, or delivered to lymphoid organs by peripheral nerves. Taken together, the experimental results obtained so far strongly point to the importance of CRF as a signaling molecule in lymphoid tissues and at the sites of inflammation.
CD8+ cytotoxic T lymphocytes (CTLs) play an important role in antitumor immunity. Induction of tumor-specific CTLs is one major strategy for tumor immunotherapy. However, therapeutic vaccinations used to treat firmly established tumors are generally ineffective. A thorough understanding of the mechanisms underlying tumor resistance to CTL-based therapeutic vaccination is very important in the tumor immunology field. There are two main mechanisms by which tumors develop resistance to CTL-based therapeutic vaccinations. One is that tumors induce peripheral tolerance of tumor-specific CD8+ T cells. The other is that tumor cells themselves develop immune evasion mechanisms to prevent recognition and killing by CTLs. This review focuses on recently reported cellular and molecular mechanisms of CD8+ T cell tolerance and immune evasion in tumors and discusses about the possibilities to improve tumor immunotherapy.
The aim of the study was to discover the mechanism of rejection of chondrocyte transplants introduced into articular cartilage defects. Chondrocytes from 3?5-day-old Lewis or WAG rats were liberated by enzymatic digesand tion from articular-epiphyseal cartilage complexes and implanted into defects made in the subpatellar region of the femur condyle of naive Lewis rats. Syngeneic transplants were also done after sensitization of the recipients with allogeneic chondrocytes injected intramuscularly. The transplants and synovial membrane were studied in periodate-lysineparaformaldehyde- fixed material with antibodies against B lymphocytes, CD4+ and CD8+ cells, NK cells, and macrophages. For detection of humoral response, chondrocyte lysates were subjected to protein electrophoresis and Western blotting with sera from the transplant recipients. Cartilage produced in intracartilaginous transplants of syngeneic chondrocytes did not show any signs of rejection. CD8+ lymphocytes and macrophages accumulated in the vicinity of cartilage produced by similar transplants in animals sensitized with intramuscular transplants of allogeneic WAG chondrocytes or bearing transplants of allogeneic WAG chondrocytes. CD8+ cells penetrated into the peripheral part of the cartilage, while macrophages advanced much more deeply. No specific anti-chondrocyte antibody was detected. The synovium from rats bearing intracartilaginous transplants of allogeneic chondrocytes or syngeneic chondrocytes after sensitization contained macrophages and CD8+ cells. The rejection of cartilage formed by syngeneic chondrocyte transplants in sensitized animals argues in favor of a chondrocyte-specific antigen expression. The involvement of the synovial membrane during transplant rejection suggests that it should be included in observations of the behavior of chondrocyte transplants introduced into articular cartilage.
The studies were performed on healthy well-trained cyclists. Maximal physical exercise was performed on a Monark bicycle ergometer according to individual schemes. Heart rate amounting to about 200 bts/min and oxygen consumption stabilization were considered as criteria for maximal physical exercise. In this study we have investigated the effect of short-term stimulation of conditioned sportsmen with thymic hormones and evaluated T cell subsets, DR antigen and transferrin receptor expression as well as mitogen-induced proliferation of lymphocytes before and after maximal physical effort. The results suggest that intensive physical exercise may be responsible for transient decrease of CD4/CD8 ratio and mitogen responsiveness, and increase of mononuclear cells number bearing HLA DR + and CD71 antigens. These changes were modified by the treatment with thymic hormones.
Fork head box P3 (FoxP3+) regulatory T cells (Tregs) are specialized T cells for the prevention of hyperimmune responses and autoimmunity. Tumors and pathogens can hijack FoxP3+ Tregs to evade host immune responses. There is an increasing body of evidence that trafficking of FoxP3+ Tregs is important for their effective suppression of target cells. Because of their distinctive functions and gene expression phenotype, the migratory behavior of FoxP3+ Tregs has been somewhat mystified. The myths are that they have unique trafficking receptors and migratory behaviors that are different from those of conventional T cells. Another related myth is that FoxP3+ regulatory T cell subsets have a fixed trafficking behavior from the time they are generated in the thymus. Recent progress in trafficking receptors and the migratory behavior of FoxP3+ Tregs are reviewed here and the validity of these myths examined.
Macrophage activation is a key determinant of susceptibility and pathology in a variety of inflammatory diseases. The extent of macrophage activation is tightly regulated by a number of pro-inflammatory cytokines (e.g. IFN-gamma, IL-2, GM-CSF, IL-3) and anti-inflammatory cytokines (e.g. IL-4, IL-10, TGF-beta). Macrophage colony stimulating factor (CSF-1/M-CSF) is a key differentiation, growth and survival factor for monocytes/macrophages and osteoclasts. The role of this factor in regulating macrophage activation is often overlooked. This review will summarise our current understanding of the effects of CSF-1 on the activation state of mature macrophages and its role in regulating immune responses.
Myelodysplastic syndromes (MDS) are hemopoietic stem cell disorders, and hemopoietic stem cell transplantation is currently the only therapeutic modality with curative potential. Among patients with less advanced/low-risk MDS (<5% marrow blasts), 3-year survivals of 65?70% are achievable with HLA-identical related and unrelated donors. The overall probability of disease recurrence in these patients is <5%. Among patients with more advanced disease (5% marrow blasts), the relapse probability is higher, ranging from 10?40%, and relapse-free survival is correspondingly lower. The criteria proposed by the International Prognostic Scoring System, derived from non-transplanted patients, also predict survival following transplantation. The development of reduced-intensity conditioning regimens and modification of conventional regimens, all aimed at optimizing the transplant approach, have permitted successful hemopoietic stem cell transplants even in patients 60?70 years of age. Improved survival with transplants from unrelated volunteer donors reflects to a large extent selection of donors on the basis of high resolution (allele-level) HLA typing. Graft-versus-host disease and associated problems remain major challenges after allogeneic transplantation. Autologous stem cell transplantation may be beneficial for selected patients who have obtained complete remissions with conventional chemotherapy.
Introduction: Experimental autoimmune encephalomyelitis (EAE) is a prototypic Th1-mediated autoimmune inflammatory disease of the central nervous system (CNS), and serves as a model for the human demyelinating disease, multiple sclerosis. Cisplatin is a drug widely used in the treatment of a variety of human neoplasias, such as advanced bladder carcinoma, adrenal cortex carcinoma, breast cancer, head and neck or lung carcinoma. Cisplatin binds to DNA and interferes with cellular repair and other mechanism, which eventually result into cell death. It is known that cisplatin can induce immunosuppressive effects through inhibition of T cell activity. Therefore we analyzed the anti-inflammatory effects of cisplatin in a rat EAE model. Materials and Methods: EAE was induced in male LEW rats by immunizing with a synthetic peptide of guinea pig myelin basic protein. The development of EAE and neurological signs were evaluated by a standard protocol. Immunohistochemistry was applied to show immune cell infiltration into the CNS. Results: Early treatment of EAE rats with cisplatin effectively ameliorated the development of disease and provided a significant protective effect compared to control rats. Further, histological analysis demonstrated that the formation of the typical perivascular cuffs and brain infiltration of monocytes and lymphocytes were complete absent in cisplatin treated rats, while abundant T cell infiltration was seen in the CNS of EAE rats. Conclusions: Our data show that cisplatin has protective effects in EAE, indicating that cisplatin could be a candidate in the treatment of human CNS autoimmunity.
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