IL-18 stimulates B-type natriuretic peptide synthesis by cardiomyocytes in vitro and its plasma levels correlate with B-type natriuretic peptide in non-overloaded acute heart failure patients

BACKGROUND

An altered IL-18 pathway in heart failure (HF) has recently been described and this cytokine was shown to be of clinical and prognostic utility. Cardiomyocytes are a target of this cytokine which exerts inflammatory, hypertrophic, and profibrotic activities. B-type natriuretic peptide is a cardiac hormone produced in response to cardiac filling to regulate cardiovascular homeostasis. The aim of the study was to verify the ability of IL-18 to induce B-type natriuretic peptide synthesis in vitro and to analyse the relationship between these two molecules in plasma in vivo from acute HF patients.

METHODS AND RESULTS

We demonstrated the ability of IL-18 to directly stimulate a murine cardiomyocyte cell line to express the B-type natriuretic peptide gene, synthesize the relative protein through a PI3K-AKT-dependent transduction, and induce a cell secretory phenotype with B-type natriuretic peptide release. A correlation between IL-18 and B-type natriuretic peptide plasma levels was found in non-overloaded acute HF patients, and in subgroups of acute HF patients with diabetes and coronary artery disease. Acute HF patients with renal failure had significantly higher IL-18 plasma levels than patients without. IL-18 plasma levels were correlated with C-reactive protein plasma levels.

CONCLUSIONS

This study provides the first evidence of the ability of IL-18 to induce B-type natriuretic peptide synthesis in vitro and outlines the relationship between the two molecules in acute HF patients with an ongoing inflammatory status.

Oxidized low density lipoprotein induced caspase-1 mediated pyroptotic cell death in macrophages: implication in lesion instability?

BACKGROUND

Macrophage death in advanced lesion has been confirmed to play an important role in plaque instability. However, the mechanism underlying lesion macrophage death still remains largely unknown.

METHODS AND RESULTS

Immunohistochemistry showed that caspase-1 activated in advanced lesion and co-located with macrophages and TUNEL positive reaction. In in-vitro experiments showed that ox-LDL induced caspase-1 activation and this activation was required for ox-LDL induced macrophages lysis, IL-1β and IL-18 production as well as DNA fragmentation. Mechanism experiments showed that CD36 and NLRP3/caspase-1/pathway involved in ox-LDL induced macrophage pyroptosis.

CONCLUSION

Our study here identified a novel cell death, pyroptosis in ox-LDL induced human macrophage, which may be implicated in lesion macrophages death and play an important role in lesion instability.

IL-18 induces airway hyperresponsiveness and pulmonary inflammation via CD4+ T cell and IL-13

IL-18 plays a key role in the pathogenesis of pulmonary inflammatory diseases including pulmonary infection, pulmonary fibrosis, lung injury and chronic obstructive pulmonary disease (COPD). However, it is unknown whether IL-18 plays any role in the pathogenesis of asthma. We hypothesized that overexpression of mature IL-18 protein in the lungs may exacerbate disease activities of asthma. We established lung-specific IL-18 transgenic mice on a Balb/c genetic background. Female mice sensitized– and challenged– with antigen (ovalbumin) were used as a mouse asthma model. Pulmonary inflammation and emphysema were not observed in the lungs of naïve transgenic mice. However, airway hyperresponsiveness and airway inflammatory cells accompanied with CD4⁺ T cells, CD8⁺ T cells, eosinophils, neutrophils, and macrophages were significantly increased in ovalbumin-sensitized and challenged transgenic mice, as compared to wild type Balb/c mice. We also demonstrate that IL-18 induces IFN-γ, IL-13, and eotaxin in the lungs of ovalbumin-sensitized and challenged transgenic mice along with an increase in IL-13 producing CD4⁺ T cells. Treatment with anti-CD4 monoclonal antibody or deletion of the IL-13 gene improves ovalbumin-induced airway hyperresponsiveness and reduces airway inflammatory cells in transgenic mice. Overexpressing the IL-18 protein in the lungs induces type 1 and type 2 cytokines and airway inflammation, and results in increasing airway hyperresponsiveness via CD4⁺ T cells and IL-13 in asthma.

Upregulated NLRP3 inflammasome activation in patients with type 2 diabetes

Despite the recent attention focused on the roles of the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in the pathogenesis of type 2 diabetes, little is known about the ex vivo profile of inflammasome activation in type 2 diabetic patients. In this study, we investigated patterns of NLRP3 inflammasome activation in monocyte-derived macrophages (MDMs) from drug-naïve patients with newly diagnosed type 2 diabetes. Type 2 diabetic subjects had significantly increased mRNA and protein expression of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and proinflammatory cytokines in MDMs cultured with autologous sera compared with healthy controls. Upregulated interleukin (IL)-1β maturation, IL-18 secretion, and caspase-1 cleavage were observed in MDMs from type 2 diabetic patients after stimulation with various danger molecules (ATP, high-mobility group protein B1, free fatty acids, islet amyloid polypeptide, and monosodium uric acid crystals). Mitochondrial reactive oxygen species and NLRP3 were required for IL-1β synthesis in MDMs. Finally, 2 months of therapy with the antidiabetic drug metformin significantly inhibited the maturation of IL-1β in MDMs from patients with type 2 diabetes through AMP-activated protein kinase (AMPK) activation. Taken together, these data suggest that NLRP3 inflammasome activation is elevated in myeloid cells from type 2 diabetic patients and that antidiabetic treatment with metformin contributes to modulation of inflammasome activation in type 2 diabetes.

Stromal-epithelial interactions modulate the effect of ovarian steroids on goat uterine epithelial cell interleukin-18 release

A primary role of epithelial-stromal interactions in mediating steroid hormone action in the uterus has been established. The present study was undertaken to determine the mode of ovarian steroid action in regulating IL-18 release by goat endometrial epithelial cells (EECs) in the presence and absence of endometrial stromal cells (ESCs). Primary and telomerase-immortalized goat EECs grown alone or cocultured with ESCs were treated with two ovarian steroids, 17β-estradiol (E(2)) and progesterone (P(4)). The IL-18 mRNA and protein expression in EECs were studied by reverse transcript (RT) PCR, ELISA, and Western blot assay. The E(2) and/or P(4) treatment of EECs led to a significant increase in both IL-18 mRNA and protein expression either in the primary or in the immortalized EECs compared with that in EECs without the steroid treatment. However, in the presence of ESCs, IL-18 expression by EECs treated with steroids was significantly decreased compared with cells untreated with E(2) and/or P(4). In addition, significantly high abundance of IL-18 mRNA and protein expression by primary and telomerase-immortalized goat EECs was observed in the presence of ESCs compared with those cells without ESCs. These findings suggest that steroids are important for the control of IL-18 expression in goat EECs. Underlying ESCs are needed to mediate the inhibitory effects of steroids on the IL-18 secretory activity of goat EECs in vitro. The IL-18 abundance expressed by goat EECs in vitro are enhanced by underlying ESCs without the treatment of E(2) and/or P(4).

The Q705K polymorphism in NLRP3 is a gain-of-function alteration leading to excessive interleukin-1β and IL-18 production

Background

The Q705K polymorphism in NLRP3 has been implicated in several chronic inflammatory diseases. In this study we determine the functional role of this commonly occurring polymorphism using an in-vitro system.

Principal Findings

NLRP3-WT and NLRP3-Q705K were retrovirally transduced into the human monocytic cell line THP-1, followed by the assessment of IL-1β and IL-18 levels in the cell culture supernatant. THP-1 cells expressing the above NLRP3 variants were sorted based upon Green Fluorescent Protein (GFP) expression. Cytokine response to alum (one of the most widely used adjuvants in vaccines) in the cells stably expressing NLRP3-WT and NLRP3-Q705K were determined. IL-1β and IL-18 levels were found to be elevated in THP-1 cells transduced with NLRP3-Q705K compared to the NLRP3-WT. Upon exposure to alum, THP-1 cells stably expressing NLRP3-Q705K displayed an increased release of IL-1β, IL-18 and TNF-α, in a caspase-1 and IL-1 receptor-dependent manner.

Conclusions

Collectively, these findings show that the Q705K polymorphism in NLRP3 is a gain-of-function alteration leading to an overactive NLRP3 inflammasome. The option of IL-1β blockade may be considered in patients with chronic inflammatory disorders that are unresponsive to conventional treatments.

[Tobacco--a producer of recombinant interleukins]

Interleukins are cytokines of highly pleiotropic activity and they have high potential for application in the treatment of cancer and autoimmune diseases. Trials of recombinant interleukin production in plants relate almost exclusively to tobacco, where through the transformation of the nuclear genome (agroinfection) monomeric (IL-2, IL-4, IL-13, IL-18), homodimeric (IL-10) and single-chain heterodimeric (IL-12) interleukins have been obtained. The expression of IL-10 as a homodimer in the chloroplast genome could not be reached. Expression of the given interleukin was obtained in the leaves, cell culture and culture of hairy roots of tobacco. Interleukins obtained in tobacco showed similar in vitro biological activity as commercial ILs produced mostly in E. coli. Glycosylated IL-13 obtained in tobacco was much more resistant to proteolytic digestion than commercial non-glycosylated IL-13; therefore in the case of sufficiently large production it could be suitable for oral administration in the treatment of type I diabetes.

The difference in IL-1beta , MIP-1alpha, IL-8 and IL-18 production between the infection of PMA activated U937 cells with recombinant vaccinia viruses inserted 2004 H5N1 influenza HA genes and NS genes

BACKGROUND

The severity of avian influenza H5N1 disease is correlated with the ability of the virus to induce an over production of proinflammatory cytokines from innate immune cells. However, the role of each virus gene is unknown. To elaborate the function of each virus gene, the recombinant vaccinia virus inserted HA and NS gene from the 2004 H5N1 virus were used in the study.

METHODS

U937 cells and PMA activated U937 cells were infected with recombinant vaccinia virus inserted with HA or NS gene. The expressions of HA and NS proteins in cells were detected on immunofluorescence stained slides using a confocal microscope. The cytokine productions in the cell supernatant were quantitated by ELISA.

RESULTS

The recombinant vaccinia virus inserted with HA genes induces the production of IL-1beta, MIP-1alpha, IL-8 and IL-18 cytokines from PMA activated U937 cells significantly more than cells infected with wild type vaccinia, whereas the recombinant vaccinia virus inserted with NS genes it was similar to that with the wild type vaccinia virus. However, there was no synergistic nor antagonistic effect of HA genes and NS genes in relation to cytokines production.

CONCLUSION

Only the HA gene from the 2004 H5N1 virus induces IL-1beta, MIP-lalpha, IL-8 and IL-18 cytokine productions from activated U937 cells. The same HA gene effect may or may not be the same in respiratory epithelial cells and this needs to be explored.

The role of the P2X₇ receptor in infectious diseases

ATP is an extracellular signal for the immune system, particularly during an inflammatory response. It is sensed by the P2X₇ receptor, the expression of which is upregulated by pro-inflammatory cytokines. Activation of the P2X₇ receptor opens a cation-specific channel that alters the ionic environment of the cell, activating several pathways, including (i) the inflammasome, leading to production of IL-1β and IL-18; (ii) the stress-activated protein kinase pathway, resulting in apoptosis; (iii) the mitogen-activated protein kinase pathway, leading to generation of reactive oxygen and nitrogen intermediates; and (iv) phospholipase D, stimulating phagosome-lysosome fusion. The P2X₇ receptor can initiate host mechanisms to remove pathogens, most particularly those that parasitise macrophages. At the same time, the P2X₇ receptor may be subverted by pathogens to modulate host responses. Moreover, recent genetic studies have demonstrated significant associations between susceptibility or resistance to parasites and bacteria, and loss-of-function or gain-of-function polymorphisms in the P2X₇ receptor, underscoring its importance in infectious disease.

A LysM and SH3-domain containing region of the Listeria monocytogenes p60 protein stimulates accessory cells to promote activation of host NK cells

Listeria monocytogenes (Lm) infection induces rapid and robust activation of host natural killer (NK) cells. Here we define a region of the abundantly secreted Lm endopeptidase, p60, that potently but indirectly stimulates NK cell activation in vitro and in vivo. Lm expression of p60 resulted in increased IFNγ production by naïve NK cells co-cultured with treated dendritic cells (DCs). Moreover, recombinant p60 protein stimulated activation of naive NK cells when co-cultured with TLR or cytokine primed DCs in the absence of Lm. Intact p60 protein weakly digested bacterial peptidoglycan (PGN), but neither muropeptide recognition by RIP2 nor the catalytic activity of p60 was required for NK cell activation. Rather, the immune stimulating activity mapped to an N-terminal region of p60, termed L1S. Treatment of DCs with a recombinant L1S polypeptide stimulated them to activate naïve NK cells in a cell culture model. Further, L1S treatment activated NK cells in vivo and increased host resistance to infection with Francisella tularensis live vaccine strain (LVS). These studies demonstrate an immune stimulating function for a bacterial LysM domain-containing polypeptide and suggest that recombinant versions of L1S or other p60 derivatives can be used to promote NK cell activation in therapeutic contexts.

[Characterization of circulating RNA in plasma as potential tool for breast cancer diagnostics]

The representation patterns of 15 cytokines RNA in blood plasma and blood cells of patients with breast cancer and apparently healthy women were investigated. Relative levels of RNA IL-8 and IL-18 in plasma of breast cancer patients are significantly increased compared with control group. At the same time no obvious differences were found in relative concentrations of these transcripts in blood cells of patients and control groups. Relative concentration of IL-8 RNA was higher in blood plasma of locally advanced compared with early breast cancer patients.

Interleukin-18 expression in pig salivary glands and salivary content changes during acute immobilization stress

Interleukin-18 (IL-18) has recently been considered a promising marker of stress responses. In this study, to evaluate IL-18 as a noninvasive stress marker in pigs, we investigated the expression of IL-18 in porcine salivary glands and its presence in saliva, and its dynamics during acute immobilization stress in pigs. IL-18 mRNA was detected robustly in the pig salivary glands by RT-PCR. Immunohistochemical staining of IL-18 protein expression revealed that the expression patterns differed among the three types of salivary glands (parotid, submandibular, and sublingual gland). IL-18 was also detected in pig saliva by ELISA, and a diurnal rhythm with a peak in the afternoon was observed. The IL-18 concentration in saliva was significantly increased during a 60-min acute immobilization stress in thirteen 5-month-old pigs. These results are the first evidence of a stress-related change of IL-18 in pig saliva. Salivary IL-18 may thus become a useful noninvasive marker for the evaluation of acute stress in pigs.

[Effect of miR-146a on IL-18 expression in mouse macrophage]

AIM

To investigate the effect of miR-146a on the Th1/Th2 cytokine expression in mouse RAW264.7 cell line and primary peritoneal macrophage.

METHODS

miR-146a mimics, mimics negative control (NC mimics), inhibitor miR-146a and inhibitor negative control (NC inhibitor) were transfected into RAW264.7 cells and freshly isolated peritoneal macrophage. IL-18, IL-5 and IL-10 expressions in the cells were measured by real time PCR.

RESULTS

MiR-146a mimics suppressed IL-18 expression (P<0.05), and miR-146a specific inhibitor increased IL-18 expression significantly (P<0.05). However, IL-5 and IL-10 expressions were not affected by both miR-146a mimics and miR-146a inhibitor transfections.

CONCLUSION

These data demonstrate at first time that miR-146a can regulate Th1 cytokine IL-18 expression, but not affect Th2 cytokine IL-5 and IL-10 expressions.

[Expression of porcine interleukin-18 in baculovirus/insect cells]

IL-18, as a polyphonic cytokine, is important in immune response and physiologic function. We designed one pair of primers, amplified the porcine IL-18 gene fused with a C-terminal 6xHistidine tag, and then subcloned into the pFastBacDual of Baculovirus transfer vector and transformed into DH10Bac containing a shuttle vector of Bacmid. After co-transfecting the recombinant plasmid into insect cells, the 18 kDa expressed protein of porcine IL-18 was detected by SDS-PAGE; the specificity of expressed protein was confirmed by Western blotting. The purified porcine IL-18 protein induced obvious proliferation of porcine T lymphocytes in vitro, which indicated that the expression of IL-18 had high biological activity.

Salmonella induced IL-23 and IL-1beta allow for IL-12 production by monocytes and Mphi1 through induction of IFN-gamma in CD56 NK/NK-like T cells

Background

The type-1 cytokine pathway plays a pivotal role in immunity against intracellular bacterial pathogens such as Salmonellae and Mycobacteria. Bacterial stimulation of pattern recognition receptors on monocytes, macrophages and dendritic cells initiates this pathway, and results in the production of cytokines that activate lymphocytes to produce interferon (IFN)-γ. Interleukin (IL)-12 and IL-23 are thought to be the key cytokines required for initiating a type-1 cytokine immune response to Mycobacteria and Salmonellae. The relative contribution of IL-23 and IL-12 to this process is uncertain.

Methodology/Principal Findings

We show that various TLR agonists induce the production of IL-23 but not IL-12 in freshly isolated human monocytes and cultured human macrophages. In addition, type 1 pro-inflammatory macrophages (Mϕ1) differentiated in the presence of GM-CSF and infected with live Salmonella produce IL-23, IL-1β and IL-18, but not IL-12. Supernatants of Salmonella-infected Mϕ1 contained more IL-18 and IL-1β as compared with supernatants of Mϕ1 stimulated with isolated TLR agonists, and induced IFN-γ production in human CD56⁺ cells in an IL-23 and IL-1β-dependent but IL-12-independent manner. In addition, IL-23 together with IL-18 or IL-1β led to the production of GM-CSF in CD56⁺ cells. Both IFN-γ and GM-CSF enhanced IL-23 production by monocytes in response to TLR agonists, as well as induced IL-12 production.

Conclusions/Significance

The findings implicate a positive feedback loop in which IL-23 can enhance its release via induction of IFN-γ and GM-CSF. The IL-23 induced cytokines allow for the subsequent production of IL-12 and amplify the IFN-γ production in the type-1 cytokine pathway.

Contribution of TIR domain-containing adapter inducing IFN-beta-mediated IL-18 release to LPS-induced liver injury in mice

BACKGROUND/AIMS

After treatment with heat-killed Propionibacterium acnes mice show dense hepatic granuloma formation. Such mice develop liver injury in an interleukin (IL)-18-dependent manner after challenge with a sublethal dose LPS. As previously shown, LPS-stimulated Kupffer cells secrete IL-18 depending on caspase-1 and Toll-like receptor (TLR)-4 but independently of its signal adaptor myeloid differentiation factor 88 (MyD88), suggesting importance of another signal adaptor TIR domain-containing adapter inducing IFN-beta (TRIF). Nalp3 inflammasome reportedly controls caspase-1 activation. Here we investigated the roles of MyD88 and TRIF in P. acnes-induced hepatic granuloma formation and LPS-induced caspase-1 activation for IL-18 release.

METHODS

Mice were sequentially treated with P. acnes and LPS, and their serum IL-18 levels and liver injuries were determined by ELISA and ALT/AST measurement, respectively. Active caspase-1 in LPS-stimulated Kupffer cells was determined by Western blotting.

RESULTS

Macrophage-ablated mice lacked P. acnes-induced hepatic granuloma formation and LPS-induced serum IL-18 elevation and liver injury. Myd88(-/-) Kupffer cells, but not Trif(-/-) cells, exhibited normal caspase-1 activation upon TLR4 engagement in vitro. Myd88(-/-) mice failed to develop hepatic granulomas after P. acnes treatment and liver injury induced by LPS challenge. In contrast, Trif(-/-) mice normally formed the hepatic granulomas, but could not release IL-18 or develop the liver injury. Nalp3(-/-) mice showed the same phenotypes of Trif(-/-) mice.

CONCLUSIONS

Propionibacterium acnes treatment MyD88-dependently induced hepatic granuloma formation. Subsequent LPS TRIF-dependently activated caspase-1 via Nalp3 inflammasome and induced IL-18 release, eventually leading to the liver injury.

Immunostimulatory activities of a low molecular weight antitumoral polysaccharide isolated from Agaricus blazei Murill (LMPAB) in Sarcoma 180 ascitic tumor-bearing mice

LMPAB is a linear beta-(1-3)-glucan we isolated from polysaccharide extract of Agaricus blazei Murill (AbM). Effects of LMPAB on splenic natural killer (NK) cell activity, splenocyte proliferation, index of spleen and thymus, IFN-gamma expression in spleen and the concentration of IL-12, IL-18 and TNF-alpha in serum of S180 ascitic tumor-bearing mice were detected. The results showed that intraperitoneal injection of LMPAB (100 mg x kg(-1) x d(-1)) significantly increased the thymus index. LMPAB augmented splenic NK cell activity in a dose-dependent manner (50-200 mg x kg(-1) x d(-1)). The concanavalin A (3 microg/ ml) stimulated splenocyte proliferation was significantly enhanced by LMPAB at dosages of 50, 100 or 200 mg x kg(-1) x d(-1). Further studies showed that LMPAB (50, 100 or 200 mg x kg(-1) x d(-1), 14d) significantly increased the production of IL-12, TNF-alpha, IL-18 and the expression IFN-gamma as determined by ELISA and immunohistochemistry, respectively. These results clearly indicate that the anti-tumor effects of LMPAB are closely associated with up-regulation of activity of NK cells, expression of IFN-gamma in spleen and the systemic level of IL-12, IL-18 and TNF-alpha in tumor-bearing mice.

Induction of interleukin-18 in atherosclerotic patients: a role for Chlamydia pneumoniae

OBJECTIVES

The present work explored gene expression and spontaneous induction of the inflammatory cytokine interleukin-18 (IL-18) in atherosclerotic patients. In addition, the effect of the chlamydial antigen heat shock protein 60 (HSP60) and lipopolysaccharide (LPS) on the induction of this mediator was examined.

SUBJECTS AND METHODS

Detection of IL-18 mRNA and protein level were assessed by in situ hybridization and immunohistochemistry, respectively, in 15 patients with coronary artery disease undergoing angiograms and 15 matching controls.

RESULTS

These experiments showed significantly high levels of spontaneously expressed IL-18 mRNA and high protein levels in patients compared to healthy controls (p < 0.0005). Cells stimulated with chlamydial HSP60 (CHSP60) and LPS showed a significantly high expression of IL-18 at the mRNA level (p < 0.0005 for CHSP60 and p < 0.005 for LPS) and an increased production of IL-18 at protein level (p < 0.0005 for CHSP60 and p < 0.005 for LPS).

CONCLUSION

This study demonstrated de novo synthesis of the inflammatory cytokine IL-18 in atherosclerosis and, furthermore, that chlamydial antigens might play a role in the immunopathological events in this disease by generating more inflammatory mediators such as IL-18.

Correlation of decreased survival and IL-18 in bone metastasis

OBJECTIVE

Previous studies have reported that serum IL-18 levels are increased in some cancers. We investigated whether IL-18 production is increased in sera and cancer cells of patients with non-small cell lung cancer (NSCLC).

PATIENTS OR MATERIALS

Serum levels of IFN-gamma and IL-18 and thioredoxin 1 (TRX1) were measured in 79 patients (51 males, 28 females, median age 67 years) with advanced NSCLC (57 adenocarcinoma, 22 squamous cell carcinoma; TNM stages IIIA [n=11], IIIB [n=24], and IV [n=44]) and 75 healthy age-matched controls (44 males, 31 females, median age 65 years) by enzyme-linked immunosorbent assay. We examined IL-18 production in the lungs and sites of bone metastasis of adenocarcinoma by immunohistochemistry.

RESULTS

Serum IL-18, IFN-gamma, and TRX1 levels in NSCLC patients were significantly (p<0.0001, p=0.0031, and p<0.0001, respectively) higher than in control subjects, while serum IFN-gamma levels in NSCLC were slightly increased. Serum IL-18, but not IFN-gamma or TRX1, levels were significantly (p=0.0102) and negatively associated with overall survival in NSCLC. The serum IL-18 level was identified as an independent prognostic factor for overall survival in multivariate survival analysis. Moreover, serum IL-18 levels were significantly (p=0.049) higher in NSCLC with bone metastasis than in NSCLC without bone metastasis. Based on immunohistochemistry, we observed that cancer cells in the lungs and bone metastases markedly produced IL-18.

CONCLUSION

Our results suggest that elevated serum IL-18 levels may be associated with IL-18 producing cancer cells in advanced NSCLC.

Cordyceps militaris induces the IL-18 expression via its promoter activation for IFN-gamma production

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps militaris, one of traditional herbal ingredient in oriental medicine, has been known to promote anticancer and immunomodulatory activities in vitro and in vivo. However, the biological mechanism of anticancer activity has been unknown.

OBJECTIVE

To investigate the effect of Cordyceps militaris extract on expression of interferon gamma (IFN-gamma) through interlukin-18 (IL-18) induction and its biological mechanism in vitro and in vivo.

MATERIALS AND METHODS

Mice were administrated orally with solution extracted from Cordyceps militaris. The transcription level of IL-18 and IFN-gamma production were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. RAW 264.7 cells were transiently transfected with pCATp1 and pCATp2 for IL-18 promoter functional analysis.

RESULTS

Cordyceps militaris extracts treatment significantly induced level of IL-18 transcription in mouse brain and liver and enhanced IL-18 transcription level and activated the IFN-gamma production in RAW 264.7 cells. Furthermore, Cordyceps militaris extract led to increase the activity of pCATp1 construct containing the 5' franking region of IL-18 promoter in RAW 264.7 cells.

CONCLUSION

Cordyceps militaris extract induced IL-18 mRNA level via enhancing of P1 promoter region result in activation of IFN-gamma production, indicating its potential as an immune activator or anticancer drug.

[Thyrocytes contribute to their own demise: the role of interleukin-18 in Hashimoto's thyroiditis]

OBJECTIVE

To investigate the IL-18 expression in the thyroid tissues of Hashimoto's thyroiditis (HT) and its cellular localization and the effect of interferon-gamma (IFN-gamma) on the interleukin- (IL)-18 expression in thyrocytes.

METHODS

RT-PCR and immunohistochemistry were used to detect the IL-18 expression and its cellular localization in the thyroid tissues biopsy specimens of 6 HT patients with normal thyroid function, 6 normal thyroid specimens resected from patients with pharyngeal carcinoma, and 16 specimens of thyroid tissues adjacent to the thyroid adenoma obtained during operation. Thyrocytes were isolated, cultured, and exposed to IL-1beta, tumor necrosis factor-alpha (TNF-alpha), or IFN-gamma for 48 h. RT-PCR and Western blotting were used to detect the IL-18 expression.

RESULTS

IL-18 mRNA expression was at an extremely low levels in the normal thyroid tissues and at a significantly higher level in the thyroid tissues of HT. Immunohistochemical staining showed that IL-18 expression was augmented in the thyroid tissues of HT and was mainly localized in the thyroid follicular cells. The IL-18 mRNA expression in the isolated human thyrocytes was dose-dependently elevated by IFN-gamma rather than TNF-alpha or IL-1beta. Western blotting showed that pro-IL-18, but not mature IL-18, was detected in the lysates of the cultured human thyrocytes and the expression of pro-IL-18 was increased by IFN-gamma.

CONCLUSION

IL-18 expression is elevated in the thyroid follicular cells of HT. IL-18 is constitutively expressed in the isolated human thyrocytes and its expression is up-regulated by IFN-gamma. Therefore, interplay between IL-18 and IFN-gamma may have an important role in the thyrocytes destruction in HT.

In vitro and in vivo modulation of the equine immune response by parapoxvirus ovis

REASON FOR PERFORMING STUDY

While immune modulators are used routinely in equine medicine, their mechanism of action is not always known.

OBJECTIVES

To determine the effect of a commercial preparation of inactivated parapoxvirus ovis (Orf virus; PPVO) on cytokine gene expression by equine peripheral blood mononuclear cells (PBMC) both in vitro and in vivo.

METHODS

PBMC were prepared from 6 mixed-breed yearlings and cultured in vitro with PPVO with or without Concanavalin A (Con A) for 24 h. Effects on the expression of IFNalpha, IFNbeta IFNgamma, TNFalpha and IL-18 were analysed by real time quantitative PCR (RT-PCR). In addition, 12 yearling horses were treated with PPVO and whole blood RNA samples were prepared at regular intervals to assess effects on in vivo cytokine gene expression. Six of those yearlings were later treated with saline and served as treatment controls. Nine additional yearlings were injected intradermally with a single dose and their injection sites biopsied at 24 and 48 h for cytokine expression.

RESULTS

In vitro culture of PBMC with PPVO led to a significant increase in IFNalpha and IFNbeta gene expression compared to mock-stimulated cultures. In addition, expression of IFNgamma and TNFalpha was significantly higher in PBMC stimulated with PPVO and Con A, than those stimulated with Con A alone. No changes were observed in IL-18 gene expression in vitro. Treatment of horses with a 3-dose regimen of PPVO resulted in elevation of IFNgamma gene expression, which was detected 24 h after the first dose and declined thereafter. Intradermal inoculation led to increased expression of IFNgamma along with IFNbeta, IL-15 and IL-18.

CONCLUSIONS

Together these results indicate that PPVO stimulated IFNgamma production both in vitro and in vivo. Increased cytokine expression could account for its immunomodulatory activity.

POTENTIAL RELEVANCE

The absence of adverse reactions and clear indications of increased expression of cytokine gene expression supports previous clinical uses for this immune modulator in those situations when increased expression of IFNgamma is warranted.

High production of IL-18 by dendritic cells induced by sera from patients with primary antibody deficiency

Predominantly antibody deficiencies are a category of primary immunodeficiency diseases, which consist of several rare disorders such as common variable immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA). We evaluated the effects of CVID and XLA patients' sera as a source of microenviromental factors on maturation and function of monocyte-derived DCs. Blood was collected from 10 CVID and 5 XLA patients before immunoglobulin replacement therapy and also from 8 healthy volunteers in order to obtain necessary sera for this study. Monocyte derived DCs were generated from blood cells obtained from healthy volunteers in the presence of GM-CSF, IL-4 and 10% serum concentrations from cases and controls. Immature DCs were incubated with monocyte conditioned medium (MCM) and TNF- in order to generate mature DCs. Interleukin 18 (IL-18) production by CD40L-activated mature DCs was measured after 24 hours of culture in vitro.IL-18 production by DCs generated in the presence of CVID and XLA patients' sera were 6.75+/-2.59 and 7.08+/-1.75 ng/ml, respectively, which were significantly higher than normal serum conditioned DCs (3.55+/-0.68) ng/ml. These results suggest that the sera of patients with predominantly antibody deficiencies may contain soluble factor(s) that can induce a significant increase in IL-18 production by DCs.