Molecular transductional mechanisms by which IFN gamma and other signals regulate macrophage development

Immune-Mediated Neuropathies: Pathophysiology and Management

Dysfunction of the immune system can result in damage of the peripheral nervous system. The immunological mechanisms, which include macrophage infiltration, inflammation and proliferation of Schwann cells, result in variable degrees of demyelination and axonal degeneration. Aetiology is diverse and, in some cases, may be precipitated by infection. Various animal models have contributed and helped to elucidate the pathophysiological mechanisms in acute and chronic inflammatory polyradiculoneuropathies (Guillain-Barre Syndrome and chronic inflammatory demyelinating polyradiculoneuropathy, respectively). The presence of specific anti-glycoconjugate antibodies indicates an underlying process of molecular mimicry and sometimes assists in the classification of these disorders, which often merely supports the clinical diagnosis. Now, the electrophysiological presence of conduction blocks is another important factor in characterizing another subgroup of treatable motor neuropathies (multifocal motor neuropathy with conduction block), which is distinct from Lewis-Sumner syndrome (multifocal acquired demyelinating sensory and motor neuropathy) in its response to treatment modalities as well as electrophysiological features. Furthermore, paraneoplastic neuropathies are also immune-mediated and are the result of an immune reaction to tumour cells that express onconeural antigens and mimic molecules expressed on the surface of neurons. The detection of specific paraneoplastic antibodies often assists the clinician in the investigation of an underlying, sometimes specific, malignancy. This review aims to discuss the immunological and pathophysiological mechanisms that are thought to be crucial in the aetiology of dysimmune neuropathies as well as their individual electrophysiological characteristics, their laboratory features and existing treatment options. Here, we aim to present a balance of discussion from these diverse angles that may be helpful in categorizing disease and establishing prognosis.

Growth hormone-mediated reprogramming of macrophage transcriptome and effector functions

Macrophages are an important component of the innate immune response. Priming and activation of macrophages is stimulated by cytokines (i.e IFNγ). However, growth hormone (GH) can also stimulate macrophage activation. Based on these observations, the goal of this work was to 1) to compare the transcriptome profile of macrophages activated in vitro with GH and IFNγ, and 2) to assess the impact of GH on key macrophage functional properties like reactive oxygen species (ROS) production and phagosomal proteolysis. To assess the global transcriptional and functional impact of GH on macrophage programming, bone marrow derived macrophages were treated with GH or IFNγ. Our data strongly support a potential link between GH, which wanes with age, and impaired macrophage function. The notable overlap of GH with IFNγ-induced pathways involved in innate immune sensing of pathogens and antimicrobial responses argue for an important role for GH in macrophage priming and maturation. By using functional assays that report on biochemical activities within the lumen of phagosomes, we have also shown that GH alters physiologically relevant processes such as ROS production and proteolysis. These changes could have far reaching impacts on antimicrobial capacity, signaling, and antigen presentation.

The acute phase of Trypanosoma cruzi infection is attenuated in 5-lipoxygenase-deficient mice

In the present work we examine the contribution of 5-lipoxygenase- (5-LO-) derived lipid mediators to immune responses during the acute phase of Trypanosoma cruzi infection in 5-LO gene knockout (5-LO(-/-)) mice and wild-type (WT) mice. Compared with WT mice, the 5-LO(-/-) mice developed less parasitemia/tissue parasitism, less inflammatory cell infiltrates, and a lower mortality. This resistance of 5-LO(-/-) mice correlated with several differences in the immune response to infection, including reduced PGE2 synthesis; sustained capacity of splenocytes to produce high levels of interleukin (IL)-12 early in the infection; enhanced splenocyte production of IL-1β, IL-6, and IFN-γ; rapid T-cell polarization to secrete high quantities of IFN-γ and low quantities of IL-10; and greater numbers of CD8(+)CD44(high)CD62L(low) memory effector T cells at the end of the acute phase of infection. The high mortality in WT mice was associated with increased production of LTB4/LTC4, T cell bias to produce IFN-γ, high levels of serum nitrite, and marked protein extravasation into the peritoneal cavity, although survival was improved by treatment with a cys-LT receptor 1 antagonist. These data also provide evidence that 5-LO-derived mediators negatively affect host survival during the acute phase of T. cruzi infection.

Synergistic activation of inflammatory cytokine genes by interferon-γ-induced chromatin remodeling and toll-like receptor signaling

Synergistic activation of inflammatory cytokine genes by interferon-γ (IFN-γ) and Toll-like receptor (TLR) signaling is important for innate immunity and inflammatory disease pathogenesis. Enhancement of TLR signaling, a previously proposed mechanism, is insufficient to explain strong synergistic activation of cytokine production in human macrophages. Rather, we found that IFN-γ induced sustained occupancy of transcription factors STAT1, IRF-1, and associated histone acetylation at promoters and enhancers at the TNF, IL6, and IL12B loci. This priming of chromatin did not activate transcription but greatly increased and prolonged recruitment of TLR4-induced transcription factors and RNA polymerase II to gene promoters and enhancers. Priming sensitized cytokine transcription to suppression by Jak inhibitors. Genome-wide analysis revealed pervasive priming of regulatory elements by IFN-γ and linked coordinate priming of promoters and enhancers with synergistic induction of transcription. Our results provide a synergy mechanism whereby IFN-γ creates a primed chromatin environment to augment TLR-induced gene transcription.

A Role for PML in Innate Immunity

The promyelocytic leukemia gene (PML) of acute promyelocytic leukemia is an established tumor suppressor gene with critical functions in growth suppression, induction of apoptosis, and cellular senescence. Interestingly, although less studied, PML seems to play a key role also in immune response to viral infection. Herein, we report that Pml(-/-) mice spontaneously develop an atypical invasive and lethal granulomatous lesion known as botryomycosis (BTM). In Pml(-/-) mice, BTM is the result of impaired function of macrophages, whereby they fail to become activated and are thus unable to clear pathogenic microorganisms. Accordingly, Pml(-/-) mice are resistant to lipopolysaccharide (LPS)-induced septic shock as a result of an ineffective production of cytokines and chemokines, suggesting a role for PML in the innate immune Toll-like receptor (TLR)/NF-κB prosurvival pathway. These results not only shed light on a new fundamental function of PML in innate immunity, but they also point to a proto-oncogenic role for PML in certain cellular and pathological contexts.

Adaptive immune regulation of glial homeostasis as an immunization strategy for neurodegenerative diseases

Neurodegenerative diseases, notably Alzheimer's and Parkinson's diseases, are amongst the most devastating disorders afflicting the elderly. Currently, no curative treatments or treatments that interdict disease progression exist. Over the past decade, immunization strategies have been proposed to combat disease progression. Such strategies induce humoral immune responses against misfolded protein aggregates to facilitate their clearance. Robust adaptive immunity against misfolded proteins, however, accelerates disease progression, precipitated by induced effector T cell responses that lead to encephalitis and neuronal death. Since then, mechanisms that attenuate such adaptive neurotoxic immune responses have been sought. We propose that shifting the balance between effector and regulatory T cell activity can attenuate neurotoxic inflammatory events. This review summarizes advances in immune regulation to achieve a homeostatic glial response for therapeutic gain. Promising new ways to optimize immunization schemes and measure their clinical efficacy are also discussed.

Control of neuroinflammation as a therapeutic strategy for amyotrophic lateral sclerosis and other neurodegenerative disorders

Neurodegenerative diseases, Alzheimer's and Parkinson's diseases, and amyotrophic lateral sclerosis (ALS) are progressive and devastating disorders of the nervous system without cure. Although a number of distinct, but not mutually exclusive, mechanisms can affect disease pathogenesis, neuroinflammation stands in common. Neuroinflammatory responses occur as a consequence of oxidative and excitotoxic neuronal damage, mitochondrial dysfunction, and protein aggregation. Thus, it is believed drugs that modulate inflammation may combat disease progression. Such strategies include those commented on in the report by Arie Neymotin et al. demonstrating lenalidomide's anti-inflammatory and neuroprotective responses in the G93A mutant superoxide dismutase-1 mouse model of ALS (Neymotin et al., 2009). While anti-inflammatory interventions may be required, they may not be sufficient to positively affect clinical outcomes. The targeting of combinations of pathogenic events including clearance of disaggregated proteins together with neuroprotective and immune modulatory strategies may all be required to facilitate positive therapeutic outcomes. This may include the targeting of both innate and adaptive neurotoxic immune responses. This commentary is designed to summarize the promises and perils in achieving immunoregulation for brain homeostatic responses and inevitable therapeutic gain. Promising new ways to optimize immunization schemes and measure their clinical efficacy are discussed with a particular focus on ALS.

Heterogeneity of microglial activation in the innate immune response in the brain

The immune response in the brain has been widely investigated and while many studies have focused on the proinflammatory cytotoxic response, the brain’s innate immune system demonstrates significant heterogeneity. Microglia, like other tissue macrophages, participate in repair and resolution processes after infection or injury to restore normal tissue homeostasis. This review examines the mechanisms that lead to reduction of self-toxicity and to repair and restructuring of the damaged extracellular matrix in the brain. Part of the resolution process involves switching macrophage functional activation to include reduction of proinflammatory mediators, increased production and release of anti-inflammatory cytokines, and production of cytoactive factors involved in repair and reconstruction of the damaged brain. Two partially overlapping and complimentary functional macrophage states have been identified and are called alternative activation and acquired deactivation. The immunosuppressive and repair processes of each of these states and how alternative activation and acquired deactivation participate in chronic neuroinflammation in the brain are discussed.

Microtubules regulate PI-3K activity and recruitment to the phagocytic cup during Fcgamma receptor-mediated phagocytosis in nonelicited macrophages

Phagocytosis is a complex sequence of events involving coordinated remodeling of the plasma membrane with the underlying cytoskeleton. Although the role of the actin cytoskeleton is becoming increasingly elucidated, the role of microtubules (MTs) remains poorly understood. Here, we examine the role of MTs during FcgammaR-mediated phagocytosis in RAW264.7 mouse macrophages. We observe that MTs extend into the phagosomal cups. The MT-depolymerizing agents, colchicine and nocodazole, cause a sizeable reduction in phagocytosis of large particles in RAW264.7 cells. Phagocytosis in primed macrophages is unaffected by MT-depolymerizing agents. However, activation of macrophages coincides with an increased population of drug-stable MTs, which persist in functional phagocytic cups. Scanning electron microscopy analysis of unprimed macrophages reveals that pseudopod formation is reduced markedly following colchicine treatment, which is not a consequence of cell rounding. MT depolymerization in these cells does not affect particle binding, Syk, or Grb2-associated binder 2 recruitment or phosphotyrosine accumulation at the site of phagocytosis. Ras activation also proceeds normally in macrophages treated with colchicine. However, MT disruption causes a decrease in accumulation of AKT-pleckstrin homology-green fluorescent protein, a probe that binds to PI-3K products at the sites of particle binding. A corresponding decline in activated AKT is observed in colchicine-treated cells using immunoblotting with a phospho-specific-AKT (ser473) antibody. Furthermore, the translocation of the p85alpha regulatory subunit of PI-3K is reduced at the phagocytic cup in colchicine-treated cells. These findings suggest that MTs regulate the recruitment and localized activity of PI-3K during pseudopod formation.

The role of the activated macrophage in clearing Listeria monocytogenes infection

Macrophage activation often contributes to the strong immune response elicited upon infection. The ability of macrophages to become activated was discovered when sub-lethal primary infections of mice with the bacterium Listeria monocytogenes provided protection against secondary infections through non-humoral immunity. L. monocytogenes infect and propagate in macrophages by escaping the phagosome into the cytosol, where they avoid humoral immune mediators. Activated macrophages kill L. monocytogenes by blocking phagosomal escape. The timing of the antimicrobial activities within the phagosome is crucial to the outcome. In non-activated macrophages, bacterial factors generally prevail, and L. monocytogenes can escape from the vacuoles and grow within cytoplasm. Activated macrophages generate reactive oxygen or nitrogen intermediates early after bacterial uptake, which prevent the bacteria from escaping vacuoles into cytoplasm. The heterogeneity in the interactions between L. monocytogenes and the macrophage indicate a complex relationship between the host and the pathogen governed by chemistries that promote and inhibit escape from vacuoles. This review examines the mechanisms used by activated and non-activated macrophages to kill microbes, and how those mechanisms are employed against L. monocytogenes.

Latency and reactivation of human cytomegalovirus

Human cytomegalovirus (HCMV) persists as a subclinical, lifelong infection in the normal human host, maintained at least in part by its carriage in the absence of detectable infectious virus – the hallmark of latent infection. Reactivation from latency in immunocompromised individuals, in contrast, often results in serious disease. Latency and reactivation are defining characteristics of the herpesviruses and key to understanding their biology. However, the precise cellular sites in which HCMV is carried and the mechanisms regulating its latency and reactivation during natural infection remain poorly understood. This review will detail our current knowledge of where HCMV is carried in healthy individuals, which viral genes are expressed upon carriage of the virus and what effect this has on cellular gene expression. It will also address the accumulating evidence suggesting that reactivation of HCMV from latency appears to be linked intrinsically to the differentiation status of the myeloid cell, and how the cellular mechanisms that normally control host gene expression play a critical role in the differential regulation of viral gene expression during latency and reactivation.

Small bowel cyclooxygenase 2 (COX-2) expression in patients with IgA nephropathy

BACKGROUND

Clinical manifestation of IgA nephropathy (IgAN) strikingly occurs after respiratory tract infections. An intestinal inflammation has also been described. We hypothesized that the intestinal inflammation should manifest itself as an increase in inflammatory cells and mucosal cyclooxygenase 2 (COX-2) expression.

METHODS

By using immunohistochemistry, we determined the phenotype and quantity of inflammatory cells in duodenal biopsy specimens from 17 IgAN patients. Control material comprised 18 patients undergoing gastroscopy because of dyspepsia.

RESULTS

All the biopsy specimens disclosed normal villous architecture. In IgAN, CD3(+) cells and COX-2-positive cells were significantly increased and J chain-producing plasma cells were significantly decreased. CD3(+) cells coexpressed COX-2 protein and COX-2-positive cells also expressed CD45RO antigen. The number of lymphocytes correlated significantly with serum IgA and COX-2-expression with serum IgA and the degree of hematuria. COX-2-positive subepithelial fibroblasts were a conspicuous finding in IgAN. In CD68(+) and CD15(+) cells, a significant increase was seen. Many of these cells also expressed COX-2 protein. CD15(+) positivity correlated significantly with proteinuria in IgAN.

CONCLUSION

Our results indicate that small bowel inflammation in IgAN shows itself as an increased number of mucosal inflammatory cells. However, polymeric IgA production is significantly decreased. An increased mucosal COX-2 expression suggests activation of the inflammatory cells and the degree of inflammation significantly correlates with serum IgA and the amount of proteinuria and hematuria. Subepithelial fibroblasts seem also to be involved in the inflammatory reaction.

Peritoneal macrophages express both P-selectin and PSGL-1

Macrophages, phagocytic cells involved in an early phase of host defense, are known to express the P-selectin ligand, PSGL-1. Heretofore, P-selectin has only been found on platelets and endothelial cells. Here, we demonstrate that peritoneal macrophages isolated by peritoneal lavage of unchallenged mice express P-selectin on the plasma membrane. The peritoneal macrophages synthesize P-selectin, as indicated by metabolic labeling experiments. P-Selectin is constitutively expressed on the extracellular surface of macrophages but is only partially colocalized with PSGL-1. P-Selectin is rapidly translocated from the macrophage plasma membrane to intracellular vesicles and to lysosomes. Peritoneal macrophages assemble into cell strings under flow conditions based upon macrophage–macrophage interactions mediated by P-selectin and PSGL-1. This is the first description of a leukocyte shown to express both P-selectin and PSGL-1.

Multinutrient undernutrition dysregulates the resident macrophage proinflammatory cytokine network, nuclear factor-kappaB activation, and nitric oxide production

We have described previously a murine model of multinutrient undernutrition that reproduced the features of moderate human malnutrition and led to increased early dissemination of Leishmania donovani. Peritoneal cells from these malnourished mice produced decreased NO after stimulation with IFN-gamma/LPS. We hypothesized that malnutrition may cause a deficit in NF-kappaB activation, a principal transcription pathway for inducible NO synthase and proinflammatory cytokines. Macrophages from malnourished mice, stimulated with IFN-gamma/LPS, showed increased IL-6 production and decreased IL-10 and TNF-alpha production. Neutralization of TNF-alpha in macrophage cultures from the control mice mimicked the effect of malnutrition on NO and IL-10 production, whereas supplemental TNF-alpha added to cultures of macrophages from malnourished mice increased NO secretion. NF-kappaB nuclear binding activity in macrophages from the malnourished mice was reduced early after stimulation, but increased to supranormal values by 16- or 24-h poststimulation. Blocking NO production in the macrophages from the control mice reproduced the effect of malnutrition on the late activation of NF-kappaB, whereas supplemental NO decreased the late NF-kappaB activation in the malnourished mice. Thus, in macrophages from the malnourished mice, initial deficits in NF-kappaB activity probably lead to decreased TNF-alpha, which results in decreased NO; however, IL-6 is regulated independently from NF-kappaB and TNF-alpha. The late activation of NF-kappaB in the macrophages from malnourished mice is due to absence of negative feedback from NO.

Tumor-associated macrophages: a molecular perspective

The "macrophage balance hypothesis" was proposed in the early 1990s to depict the complex relationship that tumor-associated macrophages (TAM) have with the neoplastic cells of the tumor. TAM represent a prominent component of the mononuclear leukocyte population of solid tumors, which displays an ambivalent relationship with tumors. They originate in the circulation and are recruited to the tumor site by tumor-derived attractants such as chemokines and interact with the tumor cells and preferentially localize at the tumor-host tissue interface, in regions often associated with low oxygen tensions. The tumor microenvironment, including cytokines and hypoxia, regulates the localization and function of TAM. Emerging evidence starts to define the molecular basis for the peculiar functional phenotype of TAM and identifies possible therapeutic targets.

African trypanosomes activate human fetal brain cells to proliferation and IFN-gamma production

We addressed the host-parasite interplay and the immunopathogenetic events occurring in the central nervous system (CNS) during human African trypanosomiasis. Human first trimester forebrain cells were stimulated with a trypanosome lymphocyte-triggering factor (TLTF) and studied for their immune response as exemplified by cell proliferation and IFN-gamma production. TLTF induced proliferation of human first trimester forebrain cells and IFN-gamma production at the mRNA and protein levels. Astrocytes are the major producers of IFN-gamma in response toTLTE These data illustrated for the first time a direct effect of a parasite factor on human brain cells. TargetingTLTF during the course of the disease may be considered in preventing the deadly neurological complications of human African trypanosomiasis. NeuroReport

Effects of Linomide on immune cells and cytokines inhibit autoimmune pathologies of the central and peripheral nervous system

Linomide (roquinimex, LS 2616) is a quinoline-3-carboxamide with pleiotropic immune modulating capacity and it has therapeutic effects in several experimental animal models of autoimmune diseases. Linomide has been evaluated in clinical trials for multiple sclerosis, and was indeed shown to have disease inhibitory effects. However, due to unexpected side effects recorded in patients treated with Linomide, premature termination of clinical trials was required. The basic mechanism(s) of action of Linomide in inducing beneficial effects in autoimmune diseases is still elusive. Some experimental evidence indicates that Linomide influences the regulation of the cytokine profile, resulting in the inhibition of autoimmune and inflammation pathologies. This review focuses on Linomide applied in models for autoimmune and inflammation pathologies of the central and the peripheral nervous system, and summarises its very encouraging disease inhibitory effects and their potential pharmacological basis. The beneficial effects recorded with Linomide in both experimental and clinical trials emphasise the possible value of substances with Linomide-like activity for clinical use in autoimmune and inflammation pathologies in the near future.

Suppression of autoimmune neuritis in IFN-gamma receptor-deficient mice

Experimental autoimmune neuritis (EAN) is an animal model of the human disease Guillain-Barré syndrome. In this autoimmune inflammatory disease, CD4(+) T cells mediate demyelination in the peripheral nervous system (PNS). Infiltrating macrophages and T cells as well as cytokines like interferon (IFN)-gamma are intimately involved in causing pathogenic effects. To investigate the role of IFN-gamma in cell-mediated EAN, IFN-gamma receptor-deficient mutant (IFN-gammaR(-/-)) C57BL/6 mice and corresponding wild-type mice were immunized with P0 peptide 180-199, a purified component of peripheral nerve myelin, and Freund's complete adjuvant. IFN-gammaR(-/-) mice exhibited later onset of clinical disease. The disease was also less severe than in wild-type mice. Fewer IL-12-producing but more IL-4-producing cells were found in sciatic nerve sections from IFN-gammaR(-/-) mice than from wild-type mice on day 24 postimmunization, i.e., at the peak of clinical EAN. At the same time, IFN-gammaR(-/-) mice had less infiltration of inflammatory cells, including macrophages, CD4(+) T cells, and monocytes, into sciatic nerve tissue and less demyelination. However, numbers of IFN-gamma-secreting cells from the spleen were significantly augmented in the IFN-gammaR(-/-) mice, reflecting a failure of negative feedback circuits. The IFN-gammaR deficiency did not affect the production of anti-P0 peptide 180-199-specific antibodies. These results indicate that IFN-gamma contributes to a susceptibility for EAN in C57BL/6 mice by promoting a Th1 cell-mediated immune response and suppressing a Th2 response.

A macrophage protein, Ym1, transiently expressed during inflammation is a novel mammalian lectin

Oral infections of mice with Trichinella spiralis induce activation of peritoneal exudate cells to transiently express and secrete a crystallizable protein Ym1. Purification of Ym1 to homogeneity was achieved. It is a single chain polypeptide (45 kDa) with a strong tendency to crystallize at its isoelectric point (pI 5.7). Co-expression of Ym1 with Mac-1 and scavenger receptor pinpoints macrophages as its main producer. Protein microsequencing data provide information required for full-length cDNA cloning from libraries constructed from activated peritoneal exudate cells. A single open reading frame of 398 amino acids with a leader peptide (21 residues) typical of secretory protein was deduced and later deposited in GenBank (accession number M94584) in 1992. By means of surface plasmon resonance analyses, Ym1 has been shown to exhibit binding specificity to saccharides with a free amine group, such as GlcN, GalN, or GlcN polymers, but it failed to bind to other saccharides. The interaction is pH-dependent but Ca2+ and Mg2+ ion-independent. The binding avidity of Ym1 to GlcN oligosaccharides was enhanced by more than 1000-fold due to the clustering effect. Specific binding of Ym1 to heparin suggests that heparin/heparan sulfate may be its physiological ligand in vivo during inflammation and/or tissue remodeling. Although it shares approximately 30% homology with microbial chitinases, no chitinase activity was found associated with Ym1. Genomic Southern blot analyses suggest that Ym1 may represent a member of a novel lectin gene family.

Amelioration of CR-EAE with lisofylline: effects on mRNA levels of IL-12 and IFN-gamma in the CNS

CR-EAE is a Th1-mediated inflammatory autoimmune demyelinating disease of the CNS and serves as a model of human multiple sclerosis. Our previous studies have shown the protective effect of orally administered lisofylline in the prevention of active and passively induced acute EAE. In our present studies we have examined the efficacy and mechanism of action of lisofylline on CR-EAE. Lisofylline decreased the number and severity of paralytic attacks in mice with relapsing EAE. The reduction of clinical disease correlated with decreased levels of mRNA levels of IFN-gamma but not of mRNA levels of IL-12. These studies suggest that lisofylline may be an effective therapeutic for established Th1 mediated autoimmune disease and that it acts by blocking IL-12R signaling and not IL-12 production in vivo.

Cyclooxygenase-2 expression in macrophages: modulation by protein kinase C-alpha

Cyclooxygenase-2 (COX-2) is an inducible enzyme responsible for high levels of PG production during inflammation and immune responses. Previous studies with pharmacological inhibitors suggested a role for protein kinase C (PKC) in PG production possibly by regulating COX-2 expression. In this study, we addressed the role of PKC-alpha in the modulation of COX-2 expression and PGE2 synthesis by the overexpressing of a dominant-negative (DN) mutant of this isoenzyme in the mouse macrophage cell line RAW 264.7. We investigated the effect of various stimuli on COX-2 expression, namely, LPS, IFN-gamma, and the intracellular parasite Leishmania donovani. Whereas LPS-induced COX-2 mRNA and protein expression were down-regulated in DN PKC-alpha-overexpressing clones, IFN-gamma-induced COX-2 expression was up-regulated in DN PKC-alpha-overexpressing clones with respect to normal RAW 264.7 cells. Measurements of PGE2 levels revealed a strong correlation between PGE2 secretion and IFN-gamma-induced COX-2 mRNA and protein levels in DN PKC-alpha-overexpressing clones. Taken together, these results suggest a role for PKC-alpha in the modulation of LPS- and IFN-gamma-induced COX-2 expression, as well as in IFN-gamma-induced PGE2 secretion.

Therapeutic efficiency of IL-2 gene transduced tumor vaccine for head and neck carcinoma

Transduction of the human interleukin-2 (IL-2) gene into tumor cells was carried out in order to develop a new immunotherapy for advanced head and neck carcinomas with a poor outcome. We transduced the IL-2 gene into KB cells, a head and neck squamous cell carcinoma cell line, using a defective herpes simplex viral (HSV) amplicon vector as a gene transfer vehicle. A high level of IL-2 was secreted by IL-2 gene-transduced KB cells (KB/IL-2). The IL-2 producibility of irradiated KB/IL-2 cells was almost the same as that of non-irradiated cells. In the tumor establishment model in nude mice, IL-2 and interferon-gamma (IFN-gamma) at high concentrations were detected in the sera of mice transplanted with KB/IL-2 cells. The spleen cells of nude mice transplanted with KB/IL-2 cells exhibited high cytotoxic activity compared to those from mice transplanted with KB cells and from untreated mice. Three of five mice transplanted with KB/IL-2 cells rejected tumors. In the treatment of established tumors, therapeutic effects due to irradiated KB/IL-2 were dose-dependent. The suppressive effects on tumor growth were blocked by anti-asialo GM1, anti-human IL-2 and anti-IFN-gamma antibodies. Immunohistochemical observation revealed the presence of asialo GM1(+) cells among the KB/IL-2 cells in tumors transplanted into nude mice.

Localization and post-Golgi trafficking of tumor necrosis factor-alpha in macrophages

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine secreted by activated macrophages. In this study, we examined the intracellular distribution and trafficking of TNF-alpha. Immunofluorescence and immunogold localization demonstrated that in lipopolysaccharide (LPS)-stimulated RAW264 macrophages, the greatest concentration of TNF-alpha is found in the perinuclear Golgi complex. Staining of the Golgi complex appeared 20 min after activation of cells and persisted for 2-12 h, and TNF-alpha appeared on the cell surface only transiently during this time. The rate of disappearance of Golgi staining correlated with the release of the cleaved, mature TNF-alpha into the medium. Pulse chase labeling and subcellular fractionation studies indicated that both 26-kDa and 17-kDa forms of TNF-alpha may be present at the level of the Golgi complex. Post-Golgi trafficking of TNF-alpha was modulated by agents that disrupt the cytoskeleton. Interferon-gamma (IFN-gamma), which primes macrophages for TNF-alpha-dependent cellular cytotoxicity, potentiated the effect of LPS by sustaining enhanced intracellular pools of TNF-alpha and also promoted redistribution of TNF-alpha into post-Golgi vesicular compartments. We propose that the primary pool of biologically active TNF-alpha in activated macrophages is held in the Golgi complex and that the cytokine is recruited directly from this intracellular pool for release in response to tumor cells or pathogens.

Orthodontic movement induces high numbers of cells expressing IFN-gamma at mRNA and protein levels

Cytokines are important signaling proteins that are liberated during immune challenges and exhibit many modulatory activities. However, their role in periodontal modeling during orthodontic tooth movement is not fully understood. The aim of this study was to analyze effects of mechanical force during orthodontic tooth movement, in the pressure zone, on the induction of interferon-gamma (IFN-gamma) as a proinflammatory cytokine of Th1 type and interleukin-4 (IL-4)/IL-10 as anti-inflammatory cytokines of Th2 type. In 12 Wistar rats 40-45 days old, the maxillary first molar was moved mesially by means of a closed coil spring for 3, 7, and 10 days. The contralateral side served as a control. IFN-gamma, IL-4, and IL-10 mRNA were determined by in situ, hybridization, and protein levels of IFN-gamma was measured by immunohistochemistry. Induction of IFN-gamma at both mRNA and protein levels was significantly higher on the experimental side than on the contralateral control side on day 3. The signal gradually became stronger on day 7 and remained high on day 10. Cytokines of the Th2 type (IL-4 and IL-10) were not detected at all examined time points in both pressure and contralateral control sides. Considering the potential immunoregulatory roles played by IFN-gamma, our data suggest that IFN-gamma may be involved in periodontium remodeling during orthodontic tooth movement.

Adversarial relationship between the leishmania lipophosphoglycan and protein kinase C of host macrophages

The dominant glycoconjugate on the cell surface of all Leishmania promastigotes is an unusual glycoconjugate named lipophosphoglycan (LPG). Its relative abundance, unique structure, and cellular location have implicated LPG as an essential virulence determinant. One feature of LPG resides in its strong inhibitory effect on the activity of protein kinase C (PKC) of host macrophages. This article summarizes the evidence that LPG is inhibitory toward PKC activation in macrophages and discusses the implication of such inhibition on intramacrophage survival of the parasite.

Cytokine profiles in the central nervous system and the spleen during the early course of experimental African trypanosomiasis

Cytokines are important signalling proteins, which have been shown to contribute to immunopathogenesis of several inflammatory and infectious diseases such as African trypanosomiasis. The present study was conducted in order to evaluate the early induction of five potential cytokines in the central nervous system (CNS) and spleens from Trypanosoma brucei brucei (T. b. brucei)-inoculated and uninfected control Sprague-Dawley rats. In brain, choroid plexus and spleen, cytokine levels were examined by in situ hybridization and immunohistochemistry, while ELISA was used to measure cytokine levels in cerebrospinal fluid (CSF). Our results showed that interferon (IFN)-gamma and transforming growth factor (TGF)-beta were highly expressed in all compartments, but low interleukin (IL)-4, IL-10 and tumour necrosis factor (TNF)-alpha mRNA levels were registered. The pattern of these cytokines is in context with the severity of the disease because (i) IFN-gamma was previously demonstrated to promote parasite growth (ii) TNF-alpha was previously demonstrated to kill the parasites and (iii) IL-4 was previously demonstrated to promote antibody production necessary for elimination of the infection. These data support the hypothesis that cytokines may have a role in developing the disease either by enhancing the parasite growth or by suppressing the immune response.

E5531, a synthetic non-toxic lipid A derivative blocks the immunobiological activities of lipopolysaccharide

1. The major pathological responses to Gram-negative bacterial sepsis are triggered by endotoxin or lipopolysaccharide. As endotoxin is shed from the bacterial outer membrane, it induces immunological responses that lead to release of a variety of cytokines and other cellular mediators. As part of a program aimed at developing a therapeutic agent for septic shock, we have developed E5531, a novel synthetic lipopolysaccharide antagonist. 2. As measured by release by tumour necrosis factor-alpha, human monocytes or whole blood can be activated by lipopolysaccharide, lipid A, and lipoteichoic acid (from Gram-positive bacteria). E5531 potently antagonizes activation by all these agents while itself being devoid of agonistic activity. 3. The inhibitory activity of E5531 was dependent on time of addition. When 10 nM E5531 was added simultaneously with lipopolysaccharide or 1 - 3 h before addition of lipopolysaccharide, production of tumour necrosis factor-alpha was inhibited by more than 98%. The addition of E5531 1 h after lipopolysaccharide reduced the efficacy of E5531 by 47%. 4. Antagonistic activity of E5531 was specific for lipopolysaccharide as it was ineffective at inhibiting interferon-gamma mediated NO release of RAW 264.7 cells, phorbor 12-myristate 13-acetate stimulated superoxide anion production in human neutrophils, concanavalin A stimulated mitogenic activity in murine thymocytes and tumor necrosis factor-alpha induced E-selectin expression in human umbilical vein endothelial cells. 5. E5531 as well as MY4, an anti-CD14 antibody, inhibited radiolabelled lipopolysaccharide binding in human monocytes. 6. These results support our contention that E5531 is a potent antagonist of lipopolysaccharide-induced release of tumour necrosis factor-alpha and other cellular mediators and may be an effective therapeutic agent for human septic shock due to Gram-negative bacteria.

A new cell enzyme-linked immunosorbent assay demonstrates gamma interferon suppression by beta interferon in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system of unknown etiology. Immune mechanisms involving the proinflammatory cytokine gamma interferon (IFN-gamma) are believed to play an important role in the pathogenesis of MS. IFN-beta-1b has been introduced as a treatment for MS and was found to reduce the number and severity of clinical exacerbations. To examine the influence of IFN-beta-1b on myelin basic protein (MBP)-specific and phytohemagglutinin-induced IFN-gamma production, we developed a cell-released capturing enzyme-linked immunosorbent assay (CRC-ELISA), which rapidly measures spontaneous and antigen- or mitogen-induced cellular IFN-gamma production. CRC-ELISA documented a significant MBP-specific T-cell response in the blood of untreated MS patients, as assessed by IFN-gamma production. This response was suppressed in MS patients treated with IFN-beta-1b. The present work confirms in vivo the in vitro suppressive effects of IFN-beta-1b on IFN-gamma production in MS. Moreover, it provides a powerful new technique for detection of cytokines.

Mice with IFN-γ Receptor Deficiency Are Less Susceptible to Experimental Autoimmune Myasthenia Gravis

IFN-γ can either adversely or beneficially affect certain experimental autoimmune diseases. To study the role of IFN-γ in the autoantibody-mediated experimental autoimmune myasthenia gravis (EAMG), an animal model of myasthenia gravis in humans, IFN-γR-deficient (IFN-γR−/−) mutant C57BL/6 mice and congenic wild-type mice were immunized with Torpedo acetylcholine receptor (AChR) plus CFA. IFN-γR−/− mice exhibited significantly lower incidence and severity of muscle weakness, lower anti-AChR IgG Ab levels, and lower Ab affinity to AChR compared with wild-type mice. Passive transfer of serum from IFN-γR−/− mice induced less muscular weakness compared with serum from wild-type mice. In contrast, numbers of lymph node cells secreting IFN-γ and of those expressing IFN-γ mRNA were strongly augmented in the IFN-γR−/− mice, reflecting a failure of negative feedback circuits. Cytokine studies by in situ hybridization revealed lower levels of lymphoid cells expressing AChR-reactive IL-1β and TNF-α mRNA in AChR + CFA-immunized IFN-γR−/− mice compared with wild-type mice. No differences were found for AChR-reactive cells expressing IL-4, IL-10, or TGF-β mRNA. These results indicate that IFN-γ promotes systemic humoral responses in EAMG by up-regulating the production and the affinity of anti-AChR autoantibodies, thereby contributing to susceptibility to EAMG in C57BL/6-type mice.

Enhanced Th1 activity and development of chronic enterocolitis in mice devoid of Stat3 in macrophages and neutrophils

We have generated mice with a cell type-specific disruption of the Stat3 gene in macrophages and neutrophils. The mutant mice are highly susceptible to endotoxin shock with increased production of inflammatory cytokines such as TNF alpha, IL-1, IFN gamma, and IL-6. Endotoxin-induced production of inflammatory cytokines is augmented because the suppressive effects of IL-10 on inflammatory cytokine production from macrophages and neutrophils are completely abolished. The mice show a polarized immune response toward the Th1 type and develop chronic enterocolitis with age. Taken together, Stat3 plays a critical role in deactivation of macrophages and neutrophils mainly exerted by IL-10.

Normal reproductive and macrophage function in Pem homeobox gene-deficient mice

Interaction between germ cells and the supporting somatic cells guides many of the differentiative processes of gametogenesis. The expression pattern of the Pem homeobox gene suggests that it may mediate specific inductive events in murine reproductive tissues. During gestation, Pem is expressed in migrating and early postmigratory primordial germ cells, as well as in all embryo-derived extraembryonic membranes. Pem expression ceases in the germline after Embryonic Day 14 in both sexes and then reappears postnatally in the supporting cells of the gonad. In mature mice, Pem is produced by testicular Sertoli cells during stages VI-VIII of spermatogenesis and transiently by ovarian granulosa cells lining periovulatory follicles. Despite this tightly regulated reproductive expression pattern, mice with a targeted mutation in Pem have normal fecundity, with no detectable alteration in extraembryonic testicular or ovarian development or function. We also show that Pem is expressed throughout embryonic and adult development in a subset of a tissue-specific class of macrophages, Kupffer cells, as well as in a localized fraction of cells in macrophage cell lines. Although the number of Pem-positive Kupffer cells increases in mice treated with lipopolysaccharide, loss of Pem does not detectably interfere with the cells' ability to induce iNOS expression, demonstrating this Kupffer cell function does not require Pem. No differences were observed between Pem-knockout mice in 129, C57BL6/J, or mixed genetic backgrounds. Together, these data show that Pem is dispensable for embryonic and postnatal development, gonadal function, and Kupffer cell activation, perhaps due to compensatory expression of a similar homeobox gene.

Tumor growth modulates macrophage nitric oxide production following paclitaxel administration

The antineoplastic agent paclitaxel (Taxol) mimics bacterial lipopolysaccharide (LPS) in normal host macrophages (Mphis), enhancing antitumor cytotoxicity in vitro. Because paclitaxel is used as an antitumor chemotherapeutic agent and tumor growth alters Mphi phenotype and function, we assessed effector molecule production and cytotoxic activity by normal host and tumor-bearing host (TBH) Mphis following paclitaxel administration. Paclitaxel treatment, duplicating human chemotherapeutic regimens, primed normal host splenic Mphis for enhanced production of the cytotoxic mediator nitric oxide (NO); in contrast, paclitaxel's NO-inducing activity was significantly suppressed in TBHs. In contrast to NO regulation, Mphi capacity for tumor necrosis factor-alpha (TNF-alpha) production in both normal hosts and TBHs was enhanced by paclitaxel administration. Although tumor growth modulated paclitaxel-induced Mphi NO production, paclitaxel administration enhanced both normal host and TBH Mphi cytotoxic antitumor activity. Blocking NO with a competitive inhibitor abrogated Mphi cytotoxicity, suggesting paclitaxel-induced TBH Mphi NO production, although suboptimal, remains sufficient to mediate antitumor activity. These data demonstrate that paclitaxel's in vivo immune activities are differentially regulated during tumor burden and suggest that paclitaxel's immunotherapeutic functions may contribute to its success as an anticancer agent.

Recovery from Guillain-Barré syndrome is associated with increased levels of neutralizing autoantibodies to interferon-gamma

Guillain-Barré syndrome (GBS) is an immune-mediated demyelinating disease of peripheral nerves that is often preceded by an infection and is usually self-restricted. The Th1 cytokine interferon-gamma (IFN-gamma) is thought to be disease-promoting in organ-specific autoimmune diseases. We report the spontaneous induction of IFN-gamma and a mechanism involving the generation of neutralizing autoantibodies (Aabs) to IFN-gamma that may regulate the disease. Numbers of cells spontaneously secreting IFN-gamma in peripheral blood were augmented in GBS, in particular at the peak of clinical disease, and decreased during recovery. This decrease was associated with elevated serum concentrations of IgG Aabs to IFN-gamma. These Aabs specifically bound to IFN-gamma and neutralized its effects in a biological assay. Aabs to IFN-gamma are proposed to be another important regulatory mechanism in IFN-gamma-driven GBS.

Clomipramine and imipramine suppress clinical signs and T and B cell response to myelin proteins in experimental autoimmune neuritis in Lewis rats

5-Hydroxytryptamine (5-HT) reuptake inhibitors of the zimeldine-type have induced polyneuropathies similar to Guillain-Barré syndrome (GBS) in patients with endogenous depression. Some monoamine neurotransmitters have been shown to affect immune reactions in vivo and in vitro in a concentration-dependent manner. We therefore studied the effect of the monoamine reuptake inhibitory anti-depressants, clomipramine and imipramine on specific immune response and the clinical course of experimental autoimmune neuritis (EAN), the animal model of GBS in humans. Clomipramine and imipramine both suppressed clinical signs of EAN induced by immunization with bovine peripheral nerve myelin (BPM), when given at a dose of 20 mg/kg/day intraperitoneally, via osmotic pumps. Clomipramine and imipramine reduced the numbers of Th1 cells secreting IFN-gamma in response to the neuritogenic myelin proteins BPM, P0 and P2 among lymph node mononuclear cells (MNC) from rats with EAN. The levels of cells secreting IgG antibodies to BPM, P2 and GM1 in lymph nodes were reduced at the height of EAN in clomipramine and imipramine treated animals. The action of clomipramine and imipramine on induced IFN-gamma and anti-myelin antibodies suggests that the mechanism for the suppressive effect of those substances on EAN symptoms may be due to an action on myelin T and B cell autoreactivity. Considering that the main common pharmacological principle of clomipramine and imipramine is to increase the functional activity of the nor-adrenaline (NA) and serotonin (5-HT) of the monoamines, it seems justified to postulate that the actions of clomipramine and imipramine demonstrated in this study to some extent involve NA and/or 5-HT. The immunomodulatory effects of clomipramine and imipramine call for further research on the potential role of drugs acting on the monoamine system in the treatment of autoimmune diseases, and for further studies of immunological mechanisms in the pathogenesis of depressive disorders.

Inhibition by sphingosine of leukemic cell killing by human monocytes activated with interleukin-2: a possible role of protein kinase C

Sphingosine and its analogs, which inhibit protein kinase C (PKC), are known to be potent inducers of apoptosis in tumor cells. However, we were concerned that sphingosine might also interfere with anti-tumor cells of the immune system. Therefore, we evaluated the effect of sphingosine on activation of human monocytes by interleukin-2 (IL-2) for killing of leukemic cells. Monocytes, purified by elutriation and adherence, were activated with IL-2 or interferon-gamma (IFN-gamma) in the presence or absence of sphingosine or another inhibitor for 18 h. Then the monocytes were washed and the culture medium was replaced with fresh medium to remove the sphingosine. HL- 60 and K562 leukemic cells were added to the monocyte cultures. Over the next 48 h, the cytotoxic activity of the monocytes towards the leukemic cells was assessed by means of an 111-indium-releasing assay. IL-2-activated monocytes lysed 48 +/- 3% of HL-60 cells and 44 +/- 3% of K562 cells. Sphingosine, dihydrosphingosine, N,N-dimethylsphingosine, and the PKC inhibitor H7 inhibited the activation of monocytes by IL-2, blocking cytotoxic activity against the leukemic cells by approximately 75%. These inhibitors were not toxic to monocytes at the concentrations used. In a PKC assay, sphingosine and H7 inhibited PKC activity in IL-2-treated monocytes. Thus, sphingosines, by inhibiting PKC activity, inhibited activation of monocytes by IL-2, which inhibited the killing of leukemic cells.

Some biological actions of alkylglycerols from shark liver oil

Shark liver oil has been used for over 40 years as both a therapeutic and preventive agent. The active ingredients in shark liver oil have been found to be a group of ether-linked glycerols known as alkylglycerols. Initial clinical use was for treating leukemias, and later to prevent radiation sickness from cancer x-ray therapy. Studies over the last 30 years have shown that alkylglycerols are multifunctional. The level of natural alkylglycerols rises within tumor cells, apparently in an effort to control cell growth. Recent studies indicate that the activation of protein kinase C, an essential step in cell proliferation, can be inhibited by alkylglycerols. This action suggests a competitive inhibition of 1.2-diacylglycerol by alkylglycerols. Further studies on the immunostimulatory action of alkylglycerols suggest a primary action on the macrophage. The process of macrophage activation has been demonstrated with both synthetic and natural alkylglycerols. While the exact mechanism has not been found, both an autocrine and paracrine system have been suggested. Shark liver is a major natural source of alkylglycerols, which have no known side effects in dosages of 100 mg three times a day. The information presented in this article suggests that alkylglycerols may be used both as an adjunct therapy in the treatment of neoplastic disorders and as an immune booster in infectious diseases.

Effect of propranolol and IFN-beta on the induction of MHC class II expression and cytokine production by IFN-gamma IN THP-1 human monocytic cells

This study was undertaken to investigate the effects of propranolol, IFN-beta, and the protein kinase modulators on IFN-gamma induction of MHC class II antigen expression and cytokine production in THP-1 human monocytic cells. IFN-gamma induced expression of HLA-DR and DQ molecules and secretion of the monokines IL-1 beta and TNF-alpha in THP-1 cells in a time and dose-dependent manner. The effect of INF-gamma on class II HLA antigens was dose-dependently inhibited by IFN-beta. H-7, phloretin, staurosporine as well as GF 109203X are selective enzyme inhibitors of protein kinase C (PKC), down-regulating IFN-gamma induced MHC class II expression and cytokine production. Stimulators of PKC, like PMA, replaced IFN-gamma in the induction of monokines in THP-1 cells, whereas the addition of HA 1004 or arachidonic acid to the culture had no effect on IFN-gamma mediated changes. Blocking of phospholipase D (PLD)-derived diacylglycerol (DAG) formation by propranolol abrogated IFN-gamma increased HLA class II expression and IL-1 beta secretion, but had little effect on IFN-gamma induced TNF-alpha production. These findings appear to suggest that PLD-derived phosphatidate is not the primary source of DAG production in IFN-gamma-induced TNF-alpha secretion, but may be necessary for IFN-gamma-mediated MHC class II induction and IL-1 beta production in human monocytes, whereas phospholipase A2 may not be required for IFN-gamma activation of PKC in the process.

Activation of Protein Kinase C-ζ and Phosphatidylinositol 3′-Kinase and Promotion of Macrophage Differentiation by Insulin-Like Growth Factor-I

Phosphoinositides that are phosphorylated at the D3 position have been reported to activate an atypical, Ca2-independent protein kinase C (PKC) isoform designated PKC-ζ, and overexpression of this enzyme leads to monocytic differentiation. In this study, we cultured human HL-60 promyeloid cells with vitamin D3 and insulin-like growth factor-I (IGF-I), a 70-amino-acid peptide that activates phosphatidylinositol 3′-kinase (PI 3-kinase) in murine promyeloid cells. Two days later, the proportion of cells differentiating into macrophages in serum-free medium, as assessed by expression of the α-subunit of the β2 integrin CD11b, increased from 5 ± 1% to 25 ± 3%. Addition of IGF-I increased the proportion of cells differentiating into CD11b-positive macrophages to 78 ± 5%. In the absence of vitamin D3, IGF-I did not induce expression of CD11b (6 ± 1%). The IGF-I-promoted macrophage differentiation was blocked specifically by preincubation of HL-60 cells with a mAb (αIR3) directed against the IGF type I receptor. Similarly, pretreatment of cells with either αIR3 or an IGF-binding protein, IGFBP-3, led to a 75% inhibition of CD11b expression when cells were cultured with vitamin D3 in serum-containing medium. IGF-I, but not vitamin D3, caused a sevenfold increase in the enzymatic activity of both PI 3-kinase and atypical PKC-ζ. Inhibition of IGF-I-inducible PI 3-kinase with either wortmannin or LY294002 abrogated the IGF-I-induced activation of PKC-ζ and totally blocked the enhancement in macrophage differentiation caused by IGF-I. These data establish that PKC-ζ is a putative downstream target of PI 3-kinase that is activated during IGF-I-promoted macrophage differentiation.

Strain difference in the induction of T-cell activation-associated, interferon gamma-dependent hepatic injury in mice

A single intravenous injection of concanavalin A (Con A) induces T-cell activation-associated inflammatory injury selectively in the liver. This study investigated the strain difference in the development of Con A-induced hepatic injury. Normal C57BL/6 and BALB/c spleen cells produced comparable levels of T-cell-derived lymphokines (interferon gamma [IFN-gamma], tumor necrosis factor alpha [TNF-alpha], and interleukin-2 [IL-2]) following in vitro stimulation with Con A. A single intravenous injection of Con A to C57BL/6 mice induced the plasma levels of TNF-alpha and IL-2 comparable with or slightly higher than those observed in BALB/c mice, whereas the same treatment resulted in an apparently lower level of IFN-gamma production in C57BL/6 mice. RNA from livers of Con A-treated C57BL/6 mice exhibited lower levels of IFN-gamma mRNA than RNA of BALB/c livers. Unexpectedly, a dramatic difference in the severity of hepatic injury was observed between C57BL/6 and BALB/c. Namely, the peak alanine transaminase (ALT) level was more than 15,000 U/L and inducible as early as 8 hours after injection of 0.2 mg Con A per mouse in the C57BL/6 strain, whereas the peak was approximately 3,000 U/L and induced as late as 24 hours after Con A injection in the BALB/c strain. The increase in plasma ALT levels was limited to less than 10% by injection of anti-IFN-gamma monoclonal antibody (mAb) in both strains. The C57BL/6 strain inducing lower levels of IFN-gamma exhibited higher IFN-gamma responsiveness as exemplified by the intrahepatic expression of an IFN-gamma-inducible gene, an inducible type of nitric oxide (NO) synthase (iNOS). These results indicate that, while IFN-gamma produced in vivo by activated T cells induces hepatic injury, there exists a striking strain difference in the induction of IFN-gamma-dependent hepatic injury.

Immunological relatedness of the protective mechanisms against tuberculosis and cancer

BACKGROUND

Bacille Calmette-Guérin (BCG), an attenuated strain of tuberculous bacillus, is the source of vaccines providing unclear and variable protection against tuberculosis (TB) and cancer. Thermostable macromolecular antigens (TMAs) are major mycobacterial complexes immunodominant in disease. A60 (TMA complex of BCG) protects mice against TB development, via T lymphocyte (TL)-mediated macrophage (Mphi) activation, halting intracellular mycobacterial replication. In most A60-primed mice, cytolytic TLs and Mphi infiltrate cancer tissue, resulting in 80-100% rejection. Adoptive TL transfer is indispensable for Mphi-dependent tumour cell inactivation via oxygen and nitrogen radicals. Neoplasm development induces immune anergy with depletion ofA60-specific TL and activated Mphi. A60 protects mice against TB and cancer by inducing the synthesis of three lymphokines: interleukin 2 (IL-2), interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha). Tumour cells prevent A60-dependent synthesis of these lymphokines in vivo and in vitro.

CONCLUSION

These data provide some clues to immune surveillance and tumour escape mechanisms, as well as to the antituberculous and antineoplastic BCG action.

Induction of autoimmune-like hepatic and ductal lesions by administration of lipopolysaccharide in mice undergoing graft-versus-host reaction across MHC class I difference

In this paper, we examined the induction of autoimmune-like histologic changes in the liver and other organs of mice undergoing graft-versus-host reaction (GVHR) with MHC class I disparity by the administration of bacterial lipopolysaccharide (LPS), on the assumption that stimulation with LPS could be an exacerbating factor. Spleen cells of C57BL/6 (B6) mice were injected twice into (B6 x bml) F1 recipient mice at an interval of 7 days to induce MHC class I GVHR and then challenged with 1 microg of LPS intravenously on the next day of the cell transfer. The hepatic lesions of the group of MHC class I GVHR mice challenged with LPS showed marked cellular infiltration at the portal area and focal necrosis was observed in the hepatic lobule. The major infiltrating cells were CD8+, and others including CD4+ cells being of minor populations. In addition, ductal lesions in extrahepatic organs, including the pancreas and salivary glands also showed marked cellular infiltration. Thus, we have demonstrated that LPS induced ductal lesions in mice with MHC class I disparity. CD8+ cells were detected at the destructive hepatic lesions, which might be effector cells. These findings indicate that LPS might be one of the potential factors which augment autoimmune-like lesions.