Cigarette smoke selectively enhances viral PAMP- and virus-induced pulmonary innate immune and remodeling responses in mice

Viral infections have more severe consequences in patients who have been exposed to cigarette smoke (CS) than in those not exposed to CS. For example, in chronic obstructive pulmonary disease (COPD), viruses cause more severe disease exacerbation, heightened inflammation, and accelerated loss of lung function compared with other causes of disease exacerbation. Symptomatology and mortality in influenza-infected smokers is also enhanced. To test the hypothesis that these outcomes are caused by CS-induced alterations in innate immunity, we defined the effects of CS on pathogen-associated molecular pattern-induced (PAMP-induced) pulmonary inflammation and remodeling in mice. CS was found to enhance parenchymal and airway inflammation and apoptosis induced by the viral PAMP poly(I:C). CS and poly(I:C) also induced accelerated emphysema and airway fibrosis. The effects of a combination of CS and poly(I:C) were associated with early induction of type I IFN and IL-18, later induction of IL-12/IL-23 p40 and IFN-gamma, and the activation of double-stranded RNA-dependent protein kinase (PKR) and eukaryotic initiation factor-2alpha (eIF2alpha). Further analysis using mice lacking specific proteins indicated a role for TLR3-dependent and -independent pathways as well as a pathway or pathways that are dependent on mitochondrial antiviral signaling protein (MAVS), IL-18Ralpha, IFN-gamma, and PKR. Importantly, CS enhanced the effects of influenza but not other agonists of innate immunity in a similar fashion. These studies demonstrate that CS selectively augments the airway and alveolar inflammatory and remodeling responses induced in the murine lung by viral PAMPs and viruses.

[Gene cloning, expression and activity detection of porcine interleukin-18 mature protein in Escherichia coli]

Porcine interleukin-18 mature protein gene was amplified from porcine spleen cells by RT-PCR. PCR product was cloned into the T vector pGEM-T for sequencing. The nucleotide sequence of this gene was 474 bp. Then, it was subcloned into the prokaryotic expressing plasmid vector pGEX6P-1 and transformed into host E. coli strain BL21 for expression. The expression of pIL-18 mature protein gene was identified by SDS-PAGE .The expression product was fusion protein with molecular weight of 45 kD and the percentage of expression protein in E. coil protein was 28%. The protein was purified by washing of inclusion bodies and the activity was measured by methyl thiazolyl tetrazolium (MTT).

Higher elastase activity associated with lower IL-18 in GCF from juvenile systemic lupus patients

PURPOSE

Our aim was to evaluate the expression of interleukin-18 (IL-18), interleukin-l-beta (IL-1beta) and the amount of elastase activity in gingival crevicular fluid (GCF) from inflamed gingival sites in patients with juvenile systemic lupus erythematosus (JSLE), and compare these to the expression in GCF from inflamed sites in generally healthy controls. In addition, the local inflammation in periodontal tissues was related to systemic inflammation by the assessment of IL-18 levels in plasma.

MATERIALS AND METHODS

GCF from 16 patients with JSLE and 14 controls were collected using a washing device. Elastase activity was measured with a specific substrate, and IL-18 and 11-1 were measured by ELISA.

RESULTS

The percentage of visible plaque index, gingival bleeding index and attachment level were similar in JSLE and controls, while the percentage of probing depth greater or equal to 3 mm was significantly higher in the controls. The total amount of IL-1beta and IL-18 in GCF were significantly decreased in JSLE, while the total amount and the percentage of free elastase activity were significantly higher in JSLE when compared with the controls. The plasma levels of I1-18 and the erythrocyte sedimentation rate were significantly higher in JSLE patients.

CONCLUSION

We found more active elastase in GCF from inflamed sites in JSLE patients even in the presence of significantly lower levels of IL-18 and IL-13. The increased elastase activity suggests a hyperactivity of neutrophils in JSLE, possibly generated by a priming effect caused by the higher plasma levels of IL-18 found in these JSLE patients.

Tissue levels of tumor necrosis factor-alpha correlates with grade of inflammation in untreated ulcerative colitis

OBJECTIVE

The immune characterization of ulcerative colitis (UC) has been unclear and controversial. One possible explanation for the discrepancies between earlier cytokine studies in UC may be the fact that the patients included were on immunosuppressive therapy. Thus, the aim of this study was to determine the tumor necrosis factor-alpha (TNF-alpha) level and T(H)1/T(H)2 cytokine expression (mRNA) profile in patients with untreated UC.

MATERIAL AND METHODS

Forty-four untreated UC patients, 10 untreated Crohn's disease (CD) patients and 28 healthy controls were included in the study. Colon biopsies were processed for quantitative measurements of TNF-alpha, interleukin (IL)-10, IL-18, IL-4 and interferon-gamma (IFN-gamma) mRNA using real-time polymerase chain reaction (PCR). TNF-alpha expression in T-cell lymphocytes (CD3) and macrophages (CD68) were further characterized by immunohistochemistry (IHC).

RESULTS

Compared with the level in normal controls, the TNF-alpha mRNA level in UC patients was clearly increased, especially in patients with moderate to severe disease. The levels of TNF-alpha mRNA increased in proportion to the UC Disease Activity Index (UCDAI) score in UC patients. Differences were also observed between UC and controls for IFN-gamma IL-18, IL-4 and IL-10. Only minor quantitative differences in cytokines were observed between UC and CD, and they were more or less similar when comparing moderate to severe UC and CD. CD3+ lymphocytes and macrophages in lamina propria from CD and UC lesions showed increased intracellular staining of TNF-alpha.

CONCLUSIONS

TNF-alpha is highly expressed in UC and correlates to the grade of inflammation. The sources of TNF-alpha were observed both in CD3+ lymphocytes and in macrophages. Cytokine expression (mRNA) profiles seem to be similar in patients with moderate to severe UC and CD.

Interleukin-18 gene polymorphisms and haplotypes in patients with oral lichen planus: a study in an ethnic Chinese cohort

Interleukin (IL)-18, a proinflammatory cytokine, induces T-helper 1 differentiation and cytotoxic T-lymphocyte functions, both of which have been proposed in the pathogenesis of oral lichen planus (OLP) - an oral disease resembles oral mucosal graft-versus-host disease (GVHD) both clinically and histologically. The aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) in the IL18 gene on the chromosome 11q22 in patients with OLP. Four SNPs of the IL18 gene at positions -137G/C (rs187238), -607C/A (rs1946518), -656G/T (rs1946519), and 1248A/G (rs189667) were analyzed in 151 patients with OLP and 143 normal controls using polymerase chain reaction-sequence-specific primers method, and the serum level of IL-18 protein was determined by enzyme-linked immunosorbent assay (ELISA). The data revealed that there is a significant difference in IL18-607 genotype distributions between the patient group and the control group (P < 0.001), and the polymorphism -137G/C also appears to be statistically associated with the more severe erosive subtype (eOLP) (P = 0.023). The identified polymorphisms at the IL-18 promoter region (i.e. -137GG) are likely to exert positive effect on the production of IL-18 protein in OLP, as detected by ELISA. Using phase software, four haplotypes were deduced from the two polymorphisms -607C/A and -137G/C, named haplotypes I to IV, and the haplotypes I, II, and IV are significantly associated with OLP (P < 0.001). Our data suggest that the identified IL18 polymorphisms may be associated with the pathogenesis of OLP in this Chinese cohort by upregulation of IL-18 production in vivo.

Immunogenicity of plasmids encoding P12A and 3C of FMDV and swine IL-18

In this paper, two recombinant plasmids (pVIR-P12AIL18-3C and pVIR-P12A-3C) containing foot and mouth disease virus (FMDV) capsid polypeptide, 3C coding regions of O/NY00 and using/or not swine IL18 as a genetic adjuvant were constructed, and evaluated for their ability to induce humoral and cellular responses in mice and swine. In addition, the ability to protect swine against homologous virus challenge was examined. Mice and swine were given booster vaccination twice and once, respectively, and swine were challenged 10 days after the booster vaccination. Control groups were inoculated with pVAX1 or phosphate-buffered saline (PBS). All animals vaccinated with pVIR-P12AIL18-3C and pVIR-P12A-3C developed specific anti-FMDV ELISA antibody and neutralizing antibody and T lymphocyte proliferation and CTL cytotoxic activity was observed. In addition, we found that pVIR-P12AIL18-3C possessed stronger immunogenicity than pVIR-P12A-3C. The pVIR-P12AIL18-3C and pVIR-P12A-3C provided full protection in 3/4 and 2/4 swine from challenge with FMDV O/NY00, respectively. The results demonstrate the potential viability of a DNA vaccine in the control and prevention of FMDV infections.

Increased IL-18 production by dendritic cells in active inflammatory myopathies

Inflammatory myopathies (IM) are chronic disorders characterized by muscular accumulation of inflammatory cells that promote cytotoxicity and tissue damage. Overexpression of chemokines and cytokines as well as imbalance of dendritic cells (DC) homeostasis have been postulated to exert a role in both dermatomyositis (DM) and polymyositis (PM). We studied the T helper (Th)-1 and Th2 cytokine levels by enzyme linked immunosorbent assay (ELISA) and the muscular expression of IL-18 and its receptor by both histochemistry (HIC) and in situ hybridization (ISH) in both patients and normal controls. Also, the cell populations infiltrating the muscles were investigated. We present evidence that DM and PM are characterized by a predominant Th1 immune response with high production of both interferon (IFN)-gamma and interleukin (IL)-18 in the presence of reduced levels of IL-4 and IL-6. IL-18 was also demonstrated in muscles and produced by both macrophages and DC surrounding either perivascular and perimysium areas or endomysium. IL-18R was highly expressed by T cells and DC as well as by endothelial cells (EC) and smooth muscle cells (SMC). High concentrations of serum and muscular IL-18 suggest that deregulated IL-18/IL-18R pathway may be pathogenetic in IM and measurement of IL-18 might be predictive of the disease activity.

[Expression and analysis of recombinant pIL-18 in Pichia pastoris]

The porcine IL-18 gene was amplified from recombinant plasmid pGEM-IL-18 by PCR, then the pPIC9K-IL-18 of fusion expression vector was constructed by inserting IL-18 fragment,and was transformed to GS115 by electroporation, multi-copy recombinant strains were screened by G418. The expression of recombinant fusion protein was induced by methanol, SDS-PAGE was used to analyze expression product, fusion protein was purified by Sephadex G-100 column, bioactivity of IL-18 was measured by MTT assays. Experiment results show fusion protein of pIL-18 secreted by GS115,expression reaches the secretion peak of 160 mg/L at 72 h. We have expressed and purified successfully the recombinant pIL-18 with obvious biological activity in Pichia pastoris.

Interleukin-18 is increased only in a minority of patients with active Crohn's disease

BACKGROUND AND AIMS

It has been suggested that Crohn's Disease (CD) is associated with an elevated T helper 1 response as manifested by increased production of interleukin-18 (IL-18). Local concentrations of neutralizing IL-18 binding proteins (IL-18 bp) may counteract biological functions of mature IL-18 in mucosal inflammation. Therefore, we investigated the IL-18/IL-18 bp system in a large group of patients with active inflammatory bowel disease (IBD) to identify patients that could respond theoretically to IL-18 neutralizing treatment strategies.

PATIENT/METHODS

IL-18 and IL-18 bp messenger RNA (mRNA) expression in colonic mucosa from patients with active CD (n = 72), active ulcerative colitis (UC; n = 32), and non-IBD controls (infectious colitis or diverticulitis; n = 19) and normal, non-diseased controls (n = 20) were measured by reverse-transcribed real-time polymerase chain reaction. Mature IL-18 protein and IL-18 bp expression in inflamed mucosa were assessed by Western blotting.

RESULTS/FINDINGS

Although IL-18 mRNA was increased in some patients with CD, the increase was not statistically significant. Densitometric evaluation of IL-18/alpha-actin ratio in patients with active CD (n = 20) and patients with UC (n = 10) demonstrated an increased ratio of IL-18 protein in CD when compared to UC (1.04 vs 0.72 [median]). On closer inspections, only 7/20 CD patients had an increased IL-18 protein expression in inflamed areas compared to noninflamed mucosa.

INTERPRETATION/CONCLUSION

IL-18 expression in active CD is heterogeneous, only a minority of patients expresses elevated levels. Further treatment strategies targeting IL-18 expression in active CD should be concentrated on this subgroup of patients.

Inflammasome activation in delayed-type hypersensitivity reactions

The inflammasome is a protein complex cleaving the pro-inflammatory cytokines IL-1beta and IL-18 into their active forms by caspase-1 activation. The cytosolic protein complex can be activated by danger signals, such as bacterial and viral components, ATP, or uric acid crystals, and reacts as a sensor of innate immunity. In the skin, sensitizing agents promote induction of specific T-cell-mediated contact hypersensitivity. They induce dendritic cell migration, a precondition for the priming of specific T cells. They are a prerequisite for the recruitment of cells into the skin that demand pro-inflammatory stimuli, such as IL-1beta and IL-18. Watanabe et al. (2007, this issue) demonstrate the presence of the inflammasome complex in keratinocytes and report that this complex can be activated by contact sensitizers, such as trinitrocholorobenzene (TNCB), both in vitro and in vivo. The study documents a regulatory effect of innate immunity in a T-cell-mediated delayed-type hypersensitivity reaction.

Allergen-induced in vitro expression of IL-18, SLAM and GATA-3 mRNA in PBMC during sublingual immunotherapy

BACKGROUND

Signalling lymphocytic activation molecule (SLAM) and interleukin (IL)-18 induce interferon (IFN)-gamma production from Th1 cells. The allergen-induced SLAM and IL-18 mRNA expressions are increased during subcutaneous immunotherapy (SCIT), but nothing is known about their role during sublingual immunotherapy (SLIT). Transcription factor GATA-3 is associated with Th2 cells but its role in SCIT and SLIT is yet unexplored. This study was undertaken to analyse the allergen induced in vitro mRNA expression of IL-18, SLAM and GATA-3 in peripheral blood mononuclear cells (PBMC) of children with allergic rhinitis (AR) during SLIT.

METHODS

Ten patients with AR undergoing pollen SLIT with a weekly dose of 200,000 SQ-U, 10 with 24,000 SQ-U of mixture of Betula verrucosa, Corylus avellana and Alnus glutinosa and 10 with placebo were included. Peripheral blood mononuclear cell were stimulated with birch extract prior to, after 1 and 2 years of the treatment. The mRNA expression was assessed using kinetic real-time RT-PCR (TaqMan); Applied Biosystems, Foster City, CA, USA).

RESULTS

The expression of IL-18 mRNA was increased in the high-dose group in comparison to the placebo group after 1 year of therapy (P = 0.028) and had an inverse correlation with the late phase skin reaction after the second study year (r = -0.41, P = 0.041). SLAM mRNA expression increased in the high-dose group from baseline to 1 year (P = 0.028) and correlated with IL-10 (r = 0.96, P < 0.0001) and transforming growth factor-beta (r = 0.80, P = 0.0037) mRNA expression. No significant changes were seen in GATA-3 mRNA expression.

CONCLUSIONS

During SLIT, IL-18 and SLAM are upregulated, suggesting that the Th2 type inflammatory response is downregulated during SLIT by increased Th1 type response.

Sphingosylphosphorylcholine activates dendritic cells, stimulating the production of interleukin-12

Compared with other lysophospholipid mediators such as sphingosine-1-phosphate and lysophosphatidic acid, little is known about the physiological significance of the related bioactive lysosphingolipid sphingosylphosphorylcholine (SPC), which is present in high-density lipoprotein particles. The present study was undertaken to evaluate the effect of SPC on human immature dendritic cells (DCs). Reverse transcription-polymerase chain reaction and flow cytometry assays revealed that DCs express two putative receptors for SPC, ovarian cancer G-protein-coupled receptor 1 and G-protein-coupled receptor 4. Exposure to SPC induced a rapid and transient increase in intracellular free calcium concentrations but did not stimulate endocytosis or chemotaxis of DCs. SPC increased the expression of HLA-DR, CD86 and CD83 and improved the T-cell priming ability of DCs, as well as the ability of DCs to stimulate the production of interferon-gamma by allogeneic peripheral blood mononuclear cells during the mixed lymphocyte reaction. Consistent with these results, we also observed that SPC stimulated the production of interleukin (IL)-12 and IL-18 by DCs. Taken together, our results support the notion that the accumulation of SPC in peripheral tissues during the course of inflammatory processes may favour the development of T helper type 1 immunity.

LPS-evoked IL-18 expression in mesangial cells plays a role in accelerating lupus nephritis

OBJECTIVES

Systemic lupus erythematosus is occasionally accompanied with bacterial infection. Lipopolysaccharide (LPS) from bacteria can accelerate and exacerbate lupus nephritis (LN) in animal models, but some mechanisms underlying the LPS-induced acceleration are still unclear. First, it is not known whether LPS can stimulate mesangial cells (MCs) to secrete the pro-inflammatory cytokine, interleukin (IL)-18. Second, it is also unclear whether LPS and/or IL-18 can induce MC apoptosis. Here, we attempted to clarify the cause-and-effect relationships between LPS stimulation, IL-18 production and MC apoptosis to address the above questions.

METHODS

LPS was used to induce accelerated LN in LN-prone mice. LPS and IL-18 were also used to treat cultured MCs isolated from the mice. IL-18 expression and MC apoptosis were investigated by in situ hybridization, the TUNEL method, reverse transcription- polymerase chain reaction (RT-PCR), western blotting, DNA electrophoresis and flow cytometry. NFkappaB was detected by immunofluorescent staining.

RESULTS

In the LPS-accelerated LN mice, we observed co-existence of IL-18 expression, hyperplasia, apoptosis, and activated apoptotic signal transduction in MCs, as well as marked neutrophil infiltration in the glomerulus, especially around the mesangial region. In cultured MCs, LPS greatly enhanced IL-18 expression, but did not induce apoptosis, while mouse IL-18 did not induce apoptosis or activate apoptotic signal transduction in MCs.

CONCLUSIONS

We conclude that LPS can evoke IL-18 production in MCs, but neither LPS nor IL-18 directly induces apoptosis or activates apoptotic signal transduction in the cells. We infer that LPS-induced IL-18 production by MCs could be a mediator by which LPS accelerates and exacerbates LN.

Adenosine A2A-receptor stimulation inhibits lipopolysaccharide-induced interleukin-18 production in monocytes

Adenosine inhibited interleukin (IL)-18 production in lipopolysaccharide (LPS)-stimulated monocytes. The action of adenosine was antagonized by an adenosine A2A-receptor (A2AR) antagonist and was mimicked by an A2AR agonist, suggesting that the stimulation of A2AR may be involved in the actions of adenosine. On the other hand, the stimulation of A1R and A3R inhibited the actions of A2AR stimulation, whereas the stimulation of A2BR had no effect on them. Activation of A2AR is known to increase cyclic adenosine monophosphate (cAMP) levels and to activate protein kinase A (PKA). A PKA inhibitor prevented the actions of A2AR stimulation, indicating that the action mechanism of A2AR stimulation may be via the activation of the cAMP/PKA pathway.

Retinal ganglion cell protection by 17-beta-estradiol in a mouse model of inherited glaucoma

Glaucoma is the second leading cause of blindness in the world. The ultimate cause of vision loss due to glaucoma is thought to be retinal ganglion cell (RGC) apoptosis. Neuroprotection of RGC is becoming an important approach of glaucoma therapy. Several lines of evidence suggest that estrogen has neurotrophic and neuroprotective properties. In this study, we examine the role of estrogen in preventing RGC loss in DBA/2J mouse, an in vivo model of an inherited (pigmentary) glaucoma. Two-month-old female DBA/2J mice were anesthetized and ovariectomized with or without subcutaneous 17beta-estradiol (betaE2) pellet implantation. RGC survival was evaluated from flat-mounted whole retinas by counting retrograde-labeled cells. The loss of nerve fibers and RGC were also evaluated in paraffin-fixed retinal cross sections. Biochemical alterations in the retinas of DBA/2J mice in response to systemic injection of betaE2 were also examined. We have made several important observations showing that: (1) betaE2 treatment reduced the loss of RGC and neurofibers through inhibition of ganglion cell apoptosis, (2) betaE2 activated Akt and cAMP-responsive-element-binding-protein (CREB), (3) betaE2 up-regulated thioredoxin-1 (Trx-1) expression, (4) betaE2 reduced the increased activations of mitogen-activated protein kinases (MAPK) and NF-kappaB, (5) betaE2 inhibited the increased interleukin-18 (IL-18) expression, and (6) treatment with tamoxifen, an estrogen receptor antagonist, blocked betaE2-mediated activation of Akt and inhibition of MAPK phosphorylation in the retinas of DBA/2J mice. These findings suggest the possible involvement of multiple biochemical events, including estrogen receptor/Akt/CREB/thioredoxin-1, and estrogen receptor/MAPK/NF-kappaB, in estrogen-mediated retinal ganglion cell protection.

Scavenger receptor A dampens induction of inflammation in response to the fungal pathogen Pneumocystis carinii

Alveolar macrophages are the effector cells largely responsible for clearance of Pneumocystis carinii from the lungs. Binding of organisms to beta-glucan and mannose receptors has been shown to stimulate phagocytosis of the organisms. To further define the mechanisms used by alveolar macrophages for clearance of P. carinii, mice deficient in the expression of scavenger receptor A (SRA) were infected with P. carinii, and clearance of organisms was monitored over time. SRA-deficient (SRAKO) mice consistently cleared P. carinii faster than did wild-type control mice. Expedited clearance corresponded to elevated numbers of activated CD4(+) T cells in the alveolar spaces of SRAKO mice compared to wild-type mice. Alveolar macrophages from SRAKO mice had increased expression of CD11b on their surfaces, consistent with an activated phenotype. However, they were not more phagocytic than macrophages expressing SRA, as measured by an in vivo phagocytosis assay. SRAKO alveolar macrophages produced significantly more tumor necrosis factor alpha (TNF-alpha) than wild-type macrophages when stimulated with lipopolysaccharide in vitro but less TNF-alpha in response to P. carinii in vitro. However, upon in vivo stimulation, SRAKO mice produced significantly more TNF-alpha, interleukin 12 (IL-12), and IL-18 in response to P. carinii infection than did wild-type mice. Together, these data indicate that SRA controls inflammatory cytokines produced by alveolar macrophages in the context of P. carinii infection.

Aluminum hydroxide adjuvants activate caspase-1 and induce IL-1beta and IL-18 release

Aluminum hydroxide (Alum) is the only adjuvant approved for routine use in humans, although the basis for its adjuvanticity remains poorly understood. In this study, we show that Alum activates caspase-1 and induce secretion of mature IL-1beta and IL-18. Human PBMC or dendritic cells stimulated with pure TLR4 and TLR2 agonists released only traces of IL-1beta or IL-18, despite the fact that the IL-1beta mRNA was readily induced by both TLR agonists. In contrast, cells costimulated with TLR agonists plus Alum released large amount of IL-1beta and IL-18. Alum-induced IL-1beta and IL-18 production was not due to enhancement of TLR signaling but rather reflected caspase-1 activation and in mouse dendritic cells occurred in a MyD88-independent fashion. Secretion of other proinflammatory cytokines such as IL-8 was not affected by Alum treatments. However, TLR-induced production of IL-10 was increased and that of IFN-gamma-inducible protein decreased by Alum cotreatment. Considering the immunostimulatory activities of these cytokines and the ability of IL-1beta to act as adjuvant, our results suggest a mechanism for the adjuvanticity of Alum.

Differential haplotypic expression of the interleukin-18 gene

Interleukin 18 (IL-18) is suspected to play an important role in atherosclerosis and plaque vulnerability. We had previously shown that haplotypes combining two IL18 gene polymorphisms in complete linkage disequilibrium, C-105T (rs360717) in 5'-untranslated region (UTR) and A+183G (rs5744292) in 3'-UTR, were related to IL-18 circulating levels and cardiovascular outcome, the C(-105) G(+183) haplotype being associated with lower IL-18 levels and lower cardiovascular risk. This study was aimed at investigating the functional role of the two polymorphisms and their haplotypes on IL18 expression levels. Allelic imbalance experiments conducted in 24 and 20 subjects heterozygous for the C-105T and the A+183G polymorphisms did not detect any difference when subjects were considered as a whole (-0.009+/-0.044, P=0.85 and +0.114+/-0.082, P=0.18, respectively). However, when splitting individuals according to their haplo-genotype, the haplotype C(-105) G(+183) was associated with a lower expression level than C(-105) A(+183) (-0.287+/-0.076, P=0.005), but did not differ from T(-105) A(+183) (-0.138+/-0.083, P=0.13). The lower expression associated with C(-105) G(+183) was confirmed by real-time reverse transcription-PCR. Transfection of different haplotypic versions of the 3'-UTR did not show any difference in the expression of an upstream reporter gene. A 10-h study of the mRNA degradation kinetics by allelic imbalance with the A+183G polymorphism did not show any differential allelic degradation. In conclusion, the haplotype associated with lower IL-18 circulating concentrations and a lower cardiovascular risk was consistently associated with decreased IL18 expression levels, although the exact functional mechanisms remain to be elucidated.

Activation of dendritic cells and induction of CD4(+) T cell differentiation by aluminum-containing adjuvants

Aluminum-containing adjuvants are widely used in licensed human and veterinary vaccines. However, the mechanism by which these adjuvants enhance the immune response and predominantly stimulate a T(H)2 humoral immune response is not well understood. In this study, the effects of aluminum hydroxide and aluminum phosphate adjuvants on antigen presentation, expression of costimulatory molecules and cytokines by mouse dendritic cells (DCs) and the ability of DCs to induce T helper cell differentiation were investigated. Dendritic cells pulsed with ovalbumin (OVA) adsorbed to aluminum-containing adjuvants activated antigen-specific T cells more effectively than DCs pulsed with OVA alone. Aluminum hydroxide adjuvant had a significantly stronger effect than aluminum phosphate adjuvant. Both aluminum-containing adjuvants significantly increased the expression of CD86 on DCs but only aluminum hydroxide adjuvant also induced moderate expression of CD80. Aluminum-containing adjuvants stimulated the release of IL-1beta and IL-18 from DCs via caspase-1 activation. DCs incubated with LPS and OVA induced T(H)1 differentiation of naïve CD4(+) T cells. In contrast, DCs incubated with aluminum/OVA activated CD4(+) T cells to secrete IL-4 and IL-5 as well as IFN-gamma. Addition of neutralizing anti-IL-1beta antibodies decreased IL-5 production and addition of anti-IL-18 antibodies decreased both IL-4 and IL-5 production. Inhibition of IL-1beta and IL-18 secretion by DCs via inhibition of caspase-1 also led to a marked decrease of IL-4 and IL-5 by CD4(+) T cells. These results indicate that aluminum-containing adjuvants activate DCs and influence their ability to direct T(H)1 and T(H)2 responses through the secretion of IL-1beta and IL-18.

Monocyte cytokine and costimulatory molecule expression in patients infected with Leishmania mexicana

Leishmania mexicana causes localized and diffuse cutaneous leishmaniasis. Patients with localized cutaneous leishmaniasis (LCL) develop a benign disease, whereas patients with diffuse cutaneous leishmaniasis (DCL) suffer from a progressive disease associated with anergy of the cellular response towards Leishmania antigens. We evaluated the production of the interleukins (IL) IL-12, IL-15, IL-18 and tumour necrosis factor-alpha (TNF-alpha) and the expression of the costimulatory molecules CD40, B7-1 and B7-2 in monocytes from LCL and DCL patients, stimulated in vitro with Leishmania mexicana lipophosphoglycan (LPG) for 18 h. LCL monocytes significantly increased TNF-alpha, IL-15 and IL-18 production, and this increase was associated with reduced amounts of IL-12. DCL monocytes produced no IL-15 or IL-18 and showed a decreasing tendency of TNF-alpha and IL-12 production as the severity of the disease increased. No difference was observed in the expression of CD40 and B7-1 between both groups of patients, yet B7-2 expression was significantly augmented in DCL patients. It remains to be established if this elevated B7-2 expression in DCL patients is cause or consequence of the Th2-type immune response that characterizes these patients. These data suggest that the diminished ability of the monocytes from DCL patients to produce cell-activating innate proinflammatory cytokines when stimulated with LPG is a possible cause for disease progression.

Inhibition of murine K-BALB and CT26 tumour growth using a Semliki Forest virus vector with enhanced expression of IL-18

The enhanced Semliki Forest virus vector (SFV10-E), an RNA-based suicide expression vector system, expresses foreign genes at levels up to 10x higher than the original SFV10 vector. This vector has been used previously to express interleukin-12 for a tumour treatment study in a BALB/c murine model. Interleukin-18, an IFN-gamma-inducing cytokine, plays a key role in the early induction of T helper1 (Th1) cell-mediated immune responses in addition to anti-angiogenic activity. In this study, the murine IL-18 gene along with an Ig-kappa leader sequence was cloned into the SFV10-E vector. The pSFV10-E-IL-18 construct was characterised in vitro for levels of expression and secretion, and the production of biologically active IL-18 was confirmed. An in vivo tumour treatment study using high titre rSFV10-E-IL-18 virus-like particles to treat subcutaneous K-BALB and CT26 tumours in BALB/c mice demonstrated therapeutic efficacy including the disappearance of tumour cells in a minority of treated animals. Tumour regression was associated with induction of avascular and suppurative necrosis.

[Effect of bone marrow stromal cells transfected with interleukin 18 on growth of intracranial glioma in rats]

BACKGROUND & OBJECTIVE

Because of the invasion and immune escape characteristics, surgical resection, radiotherapy, and chemotherapy had no definite curative effects on intracranial glioma. Because bone marrow stromal cells (BMSCs) can track migrating cells, and interleukin 18 (IL-18) can enhance antitumor immune reaction, this study was to explore the effect of IL-18-transfected BMSCs on growth of glioma in rats.

METHODS

Pure BMSCs were obtained by culturing rat bone marrow cells and identified by flow cytometry (FCM). BMSCs were transfected with retrovirus LXSN/IL-18 to prepare BMSCs/IL-18. IL-18 genetic transcription and expression were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence. The characteristic variations of BMSCs were detected by MTT assay, FCM, and immunofluorescence. The effect of BMSCs/IL-18 on activation of T cells was evaluated by ELISA. Glioma-bearing rats were divided into BMSCs group, BMSCs/IL-18 group, PBS group, and control group and received relevant treatments. The effect of BMSCs/IL-18 on growth of glioma was observed.

RESULTS

IL-18 gene was expressed stably in BMSCs/IL-18. The proliferation speed of BMSCs/IL-18 was slower than that of BMSCs. The secretion of interferon-gamma (IFN-gamma) from rat spleen lymphocytes in BMSCs/IL-18 group was 9 times more than that in BMSCs group. Tumor volume was (18.26+/-6.84) mm(3) in BMSCs group, (6.37+/-1.52) mm(3) in BMSCs/IL-18 group, (22.48+/-6.02) mm(3) in PBS group, and (21.06+/-5.83) mm(3) in control group; survival time of the rats was (25.3+/-6.4) days, (84.7+/-16.3) days, (21.6+/-4.7) days, and (22.5+/-6.2) days, respectively. After transplantation of BMSCs/IL-18, CD4(+) T cells in glioma were increased to 37.7+/-3.5 and CD8(+) T cells were increased to 32.3+/-4.5 in each field of view (x200).

CONCLUSION

BMSCs/IL-18 could express IL-18 gene stably, and have definite therapeutic effect on glioma in rats.

UVB-induced IL-18 production in human keratinocyte cell line NCTC 2544 through NF-κB activation

In the present study, we investigated the implication of NF-kappaB in the production of pro-inflammatory cytokine IL-18 by human keratinocytes stimulated by UVB. We demonstrated that NCTC 2544 keratinocyte cell line irradiated by UVB enhanced the IL-18 mRNA and protein secretion under its bioactive form. Overexpression of IL-18 by UVB irradiation was accompanied by NF-kappaB transcription factor activation using specific IL-18 gene sequence corresponding to NF-kappaB DNA binding site. The relationship between these transcription factors and IL-18 expression was confirmed using curcumin and PDTC, two inhibitors of NF-kappaB. Our results show that UVB and curcumin or PDTC co-treatment led to a down-regulation of IL-18 expression associated with an inhibition of NF-kappaB DNA binding. Hence, our results demonstrated that this transcription factor is implicated in biologically active IL-18 production by human keratinocytes irradiated by UVB.