IL-12p40 mRNA Research Articles

1045 Campylobacter Jejuni Induces Rapid and Severe Colitis in Gnotobiotic IL-10-/- Mice Through a MyD88 Independent Pathway

Introduction: The Gram-negative bacterium Campylobacter jejuni (C. jejuni) is the leading cause of food-borne diarrheal illnesses worldwide. Limited information is available on the molecular mechanisms associated with its pathogenesis. Aim: To characterize the host responses associated with C. jejuni-induced intestinal inflammation and to define themolecular mechanisms associated with the pathogenesis. Methods: Germ-free IL-10wt/wt;NF-κBEGFP and IL-10-/-;NF-κBEGFP mice were mono-associated with different amount of C. jejuni (strain 81-176; 102, 104, 106, 109cfu/mouse). IL-10-/and IL-10-/-;Myd88-/were associated with C. jejuni under specific pathogen-free (SPF) conditions (108cfu/mouse). Bacterial colonization and extraintestinal manifestations were confirmed by culturing stool, mesenteric lymph nodes (MLN), spleen and liver collected from each group and by real-time PCR (RT-PCR). Macroscopic and confocal microscopic EGFP imaging, RT-PCR analysis and histological analysis were utilized to characterize the bacteria-induced host responses. Colonoscopy was performed to document inflammation using a mini STORZ endoscope. Results: C. jejuni mono-associated IL-10-/mice developed mild (102), moderate (104) and severe (109) inflammation by day 14 as assayed by colonoscopy. Five days after association all mice had clinical signs of inflammation as evidenced by bloody diarrhea. Macroscopic analysis showed elevated EGFP expression throughout the colon of C. jejuni (109) associated IL-10-/-;NF-κBEGFP mice. All mice were colonized equally with C. jejuni as confirmed by RT-PCR and stool sample cultures. Histological analysis showed severe crypt hyperplasia, goblet cell depletion, ulcers and immune cell infiltration. TNF and IL-12p40 mRNA were significantly induced in the colon of these mice compared to WT mice. C. jejuni-induced IL-12p40, IL-23p19 and TNF gene expression was reduced in BMCD generated from IL-10-/-;Myd88-/compared to IL10-/mice. Interestingly, the onset and extent of C. jejuni-induced colitis is similar between IL-10-/-;Myd88-/and IL-10-/mice with comparable induction of TNF, Nod2, and IL-23p19 gene expression. Conclusion: Our findings indicate that C. jejuni induces rapid and severe intestinal inflammation in a susceptible host, which correlates with enhanced NF-κB activity. C. jejuni-induced colitis in IL-10-/mice appears to be mediated by a Myd88-independent pathway. These findings raise the possibility that Nod proteins are involved in C. jejuniinduced colitis.

Interferon-α and viral triggers promote functional maturation of human monocyte-derived dendritic cells

Type I interferons (IFNs) play an important role in the pathogenesis of many autoimmune disorders including psoriasis. In the presence of IFN-alpha and granulocyte/macrophage colony-stimulating factor (GM-CSF), monocytes differentiate into dendritic cells (DCs) referred to as IFN-DCs. IFN-DCs potentially mimic DC populations involved in psoriasis and express a wide range of Toll-like receptor (TLR) subtypes. Recently, it was shown that single-stranded RNA (ssRNA) triggers TLR7 and TLR8; therefore we studied ssRNA, as a surrogate for ssRNA viruses and their impact on IFN-DCs. We established culture conditions for IFN-DCs, generated from plastic adherent monocytes using GM-CSF plus IFN-alpha. For DC stimulation ssRNA40, a 20-mer ssRNA oligonucleotide was used. The phenotypic analysis of DC preparations was performed using flow cytometry. The production of various cytokines was analysed by enzyme-linked immunosorbent assay, and real-time quantitative polymerase chain reaction was used to quantify TLR and cytokine gene expression. The ability of IFN-DCs to stimulate allogeneic T-cell proliferation was evaluated in a mixed leucocyte reaction. We found that IFN-DCs express mRNA for TLR7 and TLR8 and that ssRNA stimulation significantly improves their costimulatory molecule expression, stabilizes their phenotype and enhances their capacity to stimulate naive T-cell proliferation. Unstimulated IFN-DCs did not produce bioactive interleukin (IL)-12 and produced low levels of other proinflammatory cytokines. In contrast, ssRNA stimulation led to a significant production of IL-12p70, IL-1beta, IL-6 and tumour necrosis factor alpha. IFN-DCs contained mRNA for IL-12p35, IL-12p40, IL-23p19, IL-27p28 and IL-27EBI, which was further increased by incubation with ssRNA. Our study sheds light on a potential role for IFN-alpha and viral infections in triggering DC populations in psoriasis. These results provide additional data for the better understanding of human autoimmune and antiviral responses and may also have implications for strategies developing cancer immunotherapy.

Inhibition of Interleukin-12 Production by Trypanosoma brucei in Rat Macrophages

The immune response of a host infected with Trypanosoma brucei is modulated by trypomastigotes. We examined the changes in cytokine production in T. brucei gambiense (Wellcome strain; WS) infected rats and the influence on production of interleukin (IL)-12 by macrophages. The blood concentration of interferon-gamma, tumor necrosis factor-alpha, and IL-10 increased beginning the second day after infection. However, an increase in IL-12p40 was not observed until 4 days after infection. When spleen macrophages and Kupffer cells harvested from uninfected rats and HS-P cells (a rat macrophagelike cell line) were cocultured with WS, IL-12p40 production did not change. When HS-P cells were cultured with WS, transport of nuclear factor-kappaB into the nucleus increased. Levels of macrophage colony-stimulating factor (M-CSF) and granulocyte macrophage colony-stimulating factor mRNA in the spleens and livers of WS-infected rats were high in comparison with uninfected rats, suggesting that the WS promotes macrophage proliferation. The level of IL-12p40 mRNA in HS-P cells cocultured with WS increased in response to transfection with a small interfering RNA against M-CSF or addition of anti-M-CSF antibody. These results suggest that the WS inhibits IL-12p40 mRNA production by promoting production of macrophage colony-stimulating factor by macrophages.

CD8– dendritic cells preferentially cross‐present Saccharomyces cerevisiae antigens

Mouse splenic dendritic cell (DC) subsets possess distinct antigen-presentation abilities. CD8(+) DC are specialized in cross-presentation of antigens to CD8(+) T cells, whereas CD8(-) DC are more efficient in antigen presentation to CD4(+) T cells. In this study, we examined the capacity of CD8(+) and CD8(-) DC subsets to present fungal antigens in MHC class I and II molecules to CD8(+) and CD4(+) T cells, respectively. We used ovalbumin-expressing Saccharomyces cerevisiae (yeast-OVA) as a fungal model system. Both CD8(+) and CD8(-) DC subsets phagocytosed yeast in equal amounts and uptake was mediated via dectin-1. In addition, both DC subsets induced similar OVA-specific CD4(+) T cell proliferation after incubation with yeast-OVA. However, the induction of OVA-specific CD8(+) T cell activation was largely restricted to the CD8(-) DC subset. Furthermore, only CD8(-) DC produced cytokines such as IL-10 and TNF-alpha and increased IL-23p19 and IL-23p40 mRNA levels in response to yeast. Our results strongly suggest that DC subsets have different functions in the elicitation of adaptive immune responses in vivo.

Increased expression of interleukin-23 p19 mRNA in erythema nodosum-like lesions of Behçet’s disease

Behçet's disease (BD) is a multisystemic chronic inflammatory disease with unknown aetiology. Interleukin (IL)-12, which is involved in the pathogenesis of BD, is a 70-kDa cytokine made of p35 and p40 subunits. Recently, IL-23, which is composed of a p19 subunit and a shared p40 subunit of IL-12, was discovered; as a consequence, this raises the need to re-examine previous IL-12 reports to determine whether IL-23 is also involved in BD pathogenesis. To determine whether there are changes in IL-23 in skin lesions and sera of patients with BD. For quantitative reverse transcription-polymerase chain reaction, the total cellular RNA of erythema nodosum (EN)-like skin lesions from patients with BD, psoriasis skin lesions and skin biopsy samples from normal individuals was analysed. To determine cytokine levels, sera from patients with BD and normal individuals were analysed. Increased IL-23 p19 mRNA levels were observed for both EN-like lesions of patients with BD and skin lesions of patients with psoriasis compared with normal individuals. Although we observed an elevation of IL-12/23 p40 mRNA expression in the BD lesions, this was not significant. Moreover, the levels of IL-12 p35 mRNA in BD lesions were also not significantly different from the levels in normal control skin. In addition, no significant changes were detected in serum IL-12 and IL-23 levels between patients with BD and normal control individuals, or in patients with BD before and after treatment. Increased expression of IL-23 p19 mRNA in BD lesions suggests that IL-23 may be associated with the development of the EN-like lesions in patients with active BD.

Quantitative Evaluation of Interleukin-12 P40 Gene Expression in Peripheral Blood Mononuclear Cells

The heterodimeric cytokine IL-12 (composed of a p35 and a p40 subunit) is produced primarily by monocytes, macrophages and B cells. In vitro and in vivo experiments have demonstrated the crucial role of IL-12 in initiating and establishing both innate immunity and T cell-mediated resistance to intracellular pathogens, including Leishmania donovani, Toxoplasma gondii, Listeria monocytogenes, and Mycobacterium tuberculosis. Assessment of cytokine expression has thus become crucial to understand host responses to infections. In this study, by using the reverse transcriptase-real time PCR we developed a highly specific and sensitive assay to quantitatively evaluate IL-12p40 mRNA transcription levels in peripheral blood mononuclear cells (PBMCs) stimulated with PHA vs. unstimulated cells. We also used the ELISA to evaluate bioactive IL-12 release in culture supernatants. We provide evidence that IL-12 p40 mRNA levels were significantly up-regulated in PHA-activated PBMCs. These results were correlated with data of IL-12 levels obtained by ELISA.

IL-23 P19 Expression Induced by IL-17 and IL-1β in Rheumatoid Arthritis Synovial Mononuclear Cells

Interleukin-23 (IL-23) is a novel pro-inflammatory cytokine which has been implicated to play a pathogenic role in rheumatoid arthritis (RA). This study was undertaken to investigate the IL-23 inductive activity of the proinflammatory cytokine IL-17, IL-1β and tumor necrosis factor (TNF-α) in RA synovial fluid mononuclear cells (SFMC). Expression of IL-23p19, IL-17, IL-1β and TNF-α in joint was examined by immunohistochemistry (IHC) of patients with RA and osteoarthritis (OA). The effects of IL-17 and IL-1β on expression of IL-23p19 in human SFMC from RA patients were determined by reverse transcriptase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). IL-23p19 was expressed in the RA fibroblast like synoviocyte (FLS), but not from OA FLS. Similar to the protein expression, IL-23p19 mRNA could be detected by RT-PCR in RA SFMC. IL-17 and IL-1β could induce RA SFMC to produce the IL-23p19. The effects of IL-17 were much stronger than IL-1β or TNF-α. These responses were observed in a doseresponsive manner. In addition, IL-17 or IL-1β neutralizing antibody down-regulated the expression of IL-23p19 induced by LPS in RA-SFMC. Our results demonstrate that IL-23p19 is overexpressed in RA synovium and IL-17 and IL-1β appears to upregulate the expression of IL-23p19 in RA-SFMC.

Differential activation of alveolar and peritoneal macrophages from BCG-vaccinated guinea pigs

We compared the effect of BCG vaccination on the mRNA expression of two prototypic cytokines, IL-12 (Type 1) and IL-10 (Type 2), in guinea pig resident alveolar macrophages (AM) or resident peritoneal macrophages (PM). Cells were stimulated with live or heat-killed Mycobacterium tuberculosis, and/or with recombinant guinea pig (rgp) TNF-alpha and/or rgp IFN-gamma. AM from BCG-vaccinated guinea pigs expressed significantly less IL-10 mRNA and more IL-12p40 mRNA compared to AM from naive animals following stimulation with heat-killed mycobacteria. In PM from BCG-vaccinated guinea pigs, IL-12p40 mRNA was significantly up-regulated; however, the level of IL-10 mRNA was not affected by prior vaccination. rgp TNF-alpha or rgp IFN-gamma, both alone and together, induced a significant increase of H(2)O(2) production in PM from BCG-vaccinated animals. MHC class II expression was dramatically up-regulated in PM from BCG-vaccinated animals stimulated with both rgp TNF-alpha and rgp IFN-gamma. The levels of IL-10 and IL-12p40 mRNA were significantly enhanced in PM stimulated with combinations of rgp TNF-alpha and rgp IFN-gamma, and those cells suppressed the intracellular accumulation of viable, virulent M. tuberculosis. BCG vaccination results in the differential activation of guinea pig AM and PM to promote a Type 1 cytokine milieu and control intracellular mycobacteria.

Hepatic inflammatory cytokine mRNA expression in hepatitis C virus–human immunodeficiency virus co‐infection

Although epidemiologic studies have documented that hepatitis C virus (HCV)/human immunodeficiency virus (HIV) co-infected patients have accelerated fibrogenesis, especially those with CD4+ cell counts <200 cells/mm(3), the pathogenic mechanisms are poorly understood. We investigated whether severe immunodeficiency in co-infection is associated with changes in intrahepatic inflammatory cytokine mRNA levels. We measured interferon (IFN)-gamma, tumour necrosis factor-alpha, transforming growth factor (TGF)-beta(1), interleukin (IL)-4, IL-10, IL-12p35 and IL-12p40 mRNA levels by real-time PCR performed on liver samples from HCV mono-infected (n = 19) and HCV/HIV co-infected (n = 24) patients. Co-infected patients had decreased intrahepatic mRNA levels of IFN-gamma (P = 0.09), IL-4 (P = 0.05) and IL-12p35 (P = 0.04) compared with mono-infected patients, while IL-10 was increased (P = 0.07). In co-infected patients, IFN-gamma mRNA levels increased linearly with increasing peripheral CD4+ cell counts by 1.23 times relative to the calibrator for every 100 CD4+ cells/mm(3) increase (P = 0.02). No other cytokines were significantly associated with CD4+ cell counts. In conclusion, HIV-induced lymphopenia may result in hepatic inflammatory cytokine suppression in HCV/HIV co-infection. Intrahepatic IFN-gamma levels are significantly reduced in patients with advanced immunodeficiency. Further studies are needed to assess whether decreased IFN-gamma secretion by HCV-specific CD4+ cells may account for accelerated fibrogenesis in these patients.

Cytokine Profiles in Primary and Secondary Pulmonary Granulomas of Guinea Pigs with Tuberculosis

The cytokine mRNA profiles of primary (arising from inhaled bacilli) and secondary (arising from hematogenous reseeding of the lung) granulomas from the lung lobes of bacillus Calmette-Guérin (BCG)-vaccinated and unimmunized guinea pigs challenged with virulent Mycobacterium tuberculosis by the pulmonary route were assessed in situ using laser capture microdissection (LCM) at 6 weeks after infection. The challenge dose chosen was so low that some lung lobes did not receive an implant from the airway. In unimmunized guinea pigs, some lobes contained either large, necrotic primary lesions or small, non-necrotic secondary lesions, or both. The lobes of BCG-vaccinated animals contained only non-necrotic primary tubercles, and no secondary lesions were visible. Real-time PCR analysis of the acquired RNA clearly demonstrated that primary tubercles from BCG-vaccinated guinea pigs were overwhelmed with mRNA from the anti-inflammatory cytokine, transforming growth factor (TGF)-beta, with some IFN-gamma and IL-12p40 mRNA. In contrast, primary lesions from unimmunized animals were dominated by proinflammatory TNF-alpha mRNA. The cytokine mRNA profile of secondary lesions from unimmunized animals was strikingly similar to the profile of primary lesions from BCG-vaccinated guinea pigs (i.e., a predominance of TGF-beta mRNA with some IL-12p40 and IFN-gamma mRNA), indicating that the lung lobes from which these lesions were retrieved had been naturally "vaccinated" by the time the bloodborne bacilli returned to the lung at 3 to 4 weeks after infection. Furthermore, cytokine mRNA analysis of splenic granulomas from nonvaccinated and vaccinated animals showed close resemblance to primary granulomas recovered from the lungs of the same animal, that is, high levels of TNF-alpha mRNA in unimmunized animals, and mostly TGF-beta mRNA in BCG-vaccinated guinea pigs. Taken together, these data indicate that mycobacteria returning to the lungs of unimmunized guinea pigs 3 to 4 weeks after infection induce a local cytokine response that is fundamentally different from the response to inhaled bacilli and is reminiscent of the primary response in a vaccinated animal.

Complementary JAK/STAT Signalling Is Required for the Pro-Inflammatory Effects of CD40 Ligation: Differential Effects in Human Myeloid and B Cells.

CD40L represents a strong endogenous danger signal that induces pro-inflammatory activation of CD40-expressing cells such as dendritic cells (DC), monocytes, and B cells. However, since CD40 activation alone is insufficient to induce pro-inflammatory cytokines such as IL-12p70, we studied whether CD40-mediated pro-inflammatory activity might be dependent on co-signalling pathways involving JAK/STAT. Using quantitative Western blotting, we demonstrate that JAK/STAT signalling is induced by cytokines such as IL-4, GM-CSF and IFNg, whereas CD40 activation mediates NFkB signalling. CD40L-induced IL-12p70 and IL-10 secretion in human DC, monocytes, B cells, and chronic lymphocytic leukemia (CLL) cells was measured upon complementary JAK/STAT activation by IL-4, GM-CSF and IFNg in the presence and absence of specific inhibitors of JAK2, JAK3, and pan-JAK. Whereas IL-12p70 could not be induced by CD40 ligation or by cytokines alone, IL-12p70 secretion and suppression of IL-10 was reproducibly observed after co-stimulation of CD40L with IL-4, GM-CSF, or IFNg. This effect could be completely reversed by pan-JAK inhibition. Persistence of IL-4/GM-CSF/IFNg-mediated JAK/STAT signalling as late as 12 hours following cellular activation via CD40 was required for IL-12p70 secretion as shown by the effects of delayed JAK inhibition. Similarly, persistence between 12 and 24 hours of IL-12p35 and p40 mRNA expression correlated best with the level of IL-12p70 secretion. Specific inhibition of JAK2 and JAK3 further revealed a context-dependent action of the distinct JAK family members: JAK2 showed a strong co-dominant effect in the setting of IL-4-induced JAK/STAT activity. Both, JAK2 and JAK3 were required for IL-12p70 secretion, whereas JAK2 alone was sufficient to modulate IL-10 secretion. However, in the context of IFNg-induced JAK/STAT signalling in DC, neither JAK2 nor JAK3 inhibition had effects on IL-12p70. Here, only inhibition by the pan-JAK inhibitor involving JAK1 abrogated IL-12p70 secretion, indicating that in IFNg-dependent signalling, JAK2 is apparently sub-dominant to JAK1 and had only a small enhancing effect on IL-10. This context dependence markedly differed in myeloid cells and B cells, as normal and malignant (CLL) B cells maintain a co-dominant JAK2 activity in the context of IFNg-induced JAK/STAT-signalling. In conclusion, complementary JAK/STAT signalling is required for the pro-inflammatory effects of CD40 ligation in humans, with different JAK subset predominance in myeloid and B cells. These results may open new ways of lineage-specific interfering with CD40 signals by modulating JAK/STAT activity using tyrosine kinase inhibitors.

Temporal Regulation of Interleukin-12p70 (IL-12p70) and IL-12-Related Cytokines in Splenic Dendritic Cell Subsets duringLeishmania donovaniInfection

Dendritic cells (DC) play an essential role in initiating and directing T-cell responses, in part by production of interleukin-12p70 (IL-12p70), IL-23, and IL-27. However, comparative studies on the capacity for cytokine production of DC subsets are rare. Here, we compare splenic CD8alpha+, CD4+, and double-negative (DN) DC, isolated 5 h to 28 days after Leishmania donovani infection, for (i) production of IL-12p70, (ii) accumulation of IL-12/23p40, IL-12p35, IL-23p19, and IL-27p28 mRNAs, and (iii) their capacity to direct CD4+ T-cell differentiation. At 5 h, conventional DC (cDC) accumulated mRNA for IL-12/23p40 (CD8alpha>CD4>DN), IL-23p19 (CD4>CD8alpha>DN), and IL-27p28 (CD8alpha>CD4>DN), in an infection dose-dependent manner. IL-12p70 was restricted to CD8alpha+ cDC, reflecting the subset-specific accumulation of IL-12p35 mRNA. In contrast, cDC from mice infected for 14 to 28 days accumulated little mRNA for IL-12p40 and IL-12p19, though IL-27p28 mRNA remained detectable (CD8alpha>DN>CD4). IL-12p70 secretion by CD8alpha+ cDC was also absent, reflecting deficient IL-12/23p40, rather than IL-12p35, mRNA accumulation. The capacity of CD8alpha+ cDC isolated early after infection to direct Th1 cell differentiation was mediated through IL-12/23p40, whereas this ability in CD4+ and DN cDC was independent of IL-12/23p40 and did not result from overexpression of Delta 4 Notch-like ligand. However, DN cDC produced gamma interferon (IFN-gamma) and also contained a rare population of CD11c(hi) DX5+ IFN-gamma-producing cells. Our data illustrate the extensive diversity in, and temporal regulation of, splenic cDC subsets during infection and suggest caution in interpreting data obtained with unfractionated or minimally purified DC.

Cytokine mRNA abundance in intestinal biopsies from dogs with chronic diarrhea

The differentiation between inflammatory bowel disease (IBD) and food responsive diarrhea (FRD) is difficult and no objective markers are available. We postulated that patterns of selected key cytokines would help to objectively differentiate between the two subcategories of chronic enteropathies in dogs. We studied mRNA patterns of selected cytokines in dogs with chronic enteropathies. Ten dogs with FRD (= group FRDbef) and seven dogs with IBD (= group IBDbef) were presented for endoscopy at the Small Animal Clinic, University of Bern. A control endoscopy was performed in both groups after treatment with an elimination diet for four weeks (FRDaft) or with an elimination diet combined with prednisolone for 10 weeks (IBDaft). Intestinal control samples of gastrointestinally healthy dogs from an independent study were additionally available. Dogs were clinically examined and scored using the canine IBD activity index (CIBDAI). mRNA abundance of interleukin (IL)-5, -10, -12p40, and -13, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, and interferon (IFN)-γ were analyzed in intestinal samples by reverse transcription and real time polymerase chain reaction. Median CIBDAI decreased in FRDaft (&lt;i&gt;P&lt;/i&gt; &lt; 0.01) and IBDaft (&lt;i&gt;P&lt;/i&gt; = 0.07) during treatment. In duodenum, IL-12p40 mRNA levels tended to be lower in FRDbef than in IBDbef (&lt;i&gt;P&lt;/i&gt; = 0.07). The abundance of TNF-α mRNA was higher in IBDbef than in control dogs (&lt;i&gt;P&lt;/i&gt; &lt; 0.05). IL-5 mRNA levels decreased in FRD dogs during treatment (&lt;i&gt;P&lt;/i&gt; = 0.06), and IL-10 mRNA levels decreased in IBD dogs (&lt;i&gt;P&lt;/i&gt; &lt; 0.05). In colon, IL-5 and IL-12p40 mRNA levels were lower in FRDbef than in IBDbef (&lt;i&gt;P&lt;/i&gt; &lt; 0.05) and control dogs (&lt;i&gt;P&lt;/i&gt; &lt; 0.01). IL-13 mRNA abundance was lower in FRDbef than in control dogs (&lt;i&gt;P&lt;/i&gt; &lt; 0.05) and IFN-γ mRNA abundance was lower in FRD and IBD dogs than in control dogs (&lt;i&gt;P&lt;/i&gt; &lt; 0.01). Feeding the elimination diet additionally reduced IFN-γ mRNA levels (&lt;i&gt;P&lt;/i&gt; &lt; 0.01), but increased TNF-α mRNA levels (&lt;i&gt;P&lt;/i&gt; &lt; 0.05) in FRD dogs. In conclusion, mRNA levels of the selected cytokines before treatment did not show clear differences between FRD and IBD dogs.

Complement Receptor 3 Blockade Promotes IL-12-Mediated Clearance of Porphyromonas gingivalis and Negates Its Virulence In Vivo

The ability of certain pathogens to exploit innate immune function allows them to undermine immune clearance and thereby increase their persistence and capacity to cause disease. Porphyromonas gingivalis is a major pathogen in periodontal disease and is associated with increased risk of systemic conditions. We have previously shown that the fimbriae of P. gingivalis interact with complement receptor 3 (CR3; CD11b/CD18) in monocytes/macrophages, resulting in inhibition of IL-12p70 production in vitro. The in vivo biological implications of this observation were investigated in this study using a CR3 antagonist (XVA143). XVA143 was shown to block CR3 binding of P. gingivalis fimbriae and reverse IL-12p70 inhibition; specifically, CR3 blockade resulted in inhibition of ERK1/2 phosphorylation and up-regulation of IL-12 p35 and p40 mRNA expression. Importantly, mice pretreated with XVA143 elicited higher IL-12p70 and IFN-gamma levels in response to P. gingivalis i.p. infection and displayed enhanced pathogen clearance, compared with similarly infected controls. The notion that CR3 is associated with reduced IL-12p70 induction and impaired P. gingivalis clearance was confirmed using i.p. infected wild-type and CR3-deficient mice. Moreover, XVA143 dramatically attenuated the persistence and virulence of P. gingivalis in experimental mouse periodontitis, as evidenced by reduced induction of periodontal bone loss. Therefore, CR3 blockade may represent a promising immunomodulatory approach for controlling human periodontitis and possibly associated systemic diseases.

Ifi202, an IFN-inducible candidate gene for lupus susceptibility in NZB/W F1 mice, is a positive regulator for NF- B activation in dendritic cells

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the presence of autoantibodies and lupus nephritis. The [New Zealand black (NZB) x New Zealand white (NZW)]F1 (BWF1) mouse has been recognized as an important animal model of human SLE. The T(h)1-prone phenotype of BWF1 mice has been shown to contribute to the development of the lupus. However, the molecular basis for T(h)1 skewing in BWF1 mice has not been clarified. We noticed that IL-6, IL-12 and other proinflammatory cytokines as well as IkappaB-zeta induction were higher in mature bone marrow-derived dendritic cells (BMDCs) from NZB and BWF1 mice than those from NZW mice. The expression of an IFN-inducible gene Ifi202, a candidate gene for lupus, was almost undetectable in NZW BMDCs. Thus, we hypothesized that Ifi202 is involved in elevated IL-12 production from BWF1 BMDCs. Overexpression of Ifi202 enhanced the LPS-induced IkappaB-zeta, IL-12p40 and NF-kappaB promoter activities, while anti-sense (AS) RNA against Ifi202 strongly suppressed them in a monocytic cell line, RAW 264.7. Furthermore, overexpression of Ifi202 enhanced LPS-induced IL-12p40 and IkappaB-zeta mRNA induction while Ifi202 AS RNA suppressed these in RAW 264.7 cells. In addition, forced expression of Ifi202 enhanced IL-12p40 mRNA induction in NZW BMDCs. Thus, Ifi202 is an important NF-kappaB activator in DCs and involved in IL-12 production, which may account for a T(h)1-prone phenotype of BWF1 mice.

Expression of IL-27 p28 by Theiler's virus-infected macrophages depends on TLR3 and TLR7 activation of JNK-MAP-kinases

Theiler's murine encephalomyelitis virus (TMEV) causes a demyelinating disease (DD) due to infection of macrophages, stimulation of macrophage Toll-like receptor (TLR)3 and TLR7 pathways, activation of Mitogen-activated protein kinases (MAPK)s, and production of macrophages cytokines. Because expression of IL-27, a macrophage cytokine composed of p28 and EBI3 subunits, has been implicated in DD, we examined IL-27 subunit mRNA expression during TMEV infection of RAW264.7 cells, a macrophage cell line. TMEV infection of RAW264.7 cells did not affect cell viability, resulted in viral RNA replication, as well as p28 and EBI3 expression. Expression of p28 in TMEV-infected RAW264.7 cells depended on TLR3 and TLR7, as well as JNK but not p38 or ERK MAPKs. Since TMEV causes DD in SJL/J but not B10.S mice we determined the difference in expression of IL-27 subunit mRNA in SJL/J compared to B10.S macrophages. SJL/J macrophages expressed significantly more p28 mRNA after TMEV infection and after stimulation with TLR3 and TLR7 agonists compared with B10.S macrophages. Therefore, macrophages expression of IL-27 p28 mRNA in response to TMEV is due to activation of TLR3, TLR7, and JNK MAPKs pathways.

NKT Cells Are Critical to Initiate an Inflammatory Response after Pseudomonas aeruginosa Ocular Infection in Susceptible Mice

CD4(+) T cells produce IFN-gamma contributing to corneal perforation in C57BL/6 (B6) mice after Pseudomonas aeruginosa infection. To determine the role of NK and NKT cells, infected corneas of B6 mice were dual immunolabeled. Initially, more NKT than NK cells were detected, but as disease progressed, NK cells increased, while NKT cells decreased. Therefore, B6 mice were depleted of NK/NKT cells with anti-asialo GM1 or anti-NK1.1 Ab. Either treatment accelerated time to perforation, increased bacterial load and polymorphonuclear neutrophils, but decreased IFN-gamma and IL-12p40 mRNA expression vs controls. Next, RAG-1 knockout (-/-; no T/NKT cells), B6.TCR Jalpha281(-/-) (NKT cell deficient), alpha-galactosylceramide (alphaGalCer) (anergized NKT cells) injected and IL-12p40(-/-) vs B6 controls were tested. IFN-gamma mRNA was undetectable in RAG-1(-/-)- and alphaGalCer-treated mice at 5 h and was significantly reduced vs controls at 1 day postinfection. It also was reduced significantly in B6.TCR Jalpha281(-/-), alphaGalCer-treated, and IL-12p40(-/-) (activated CD4(+) T cells also reduced) vs control mice at 5 days postinfection. In vitro studies tested whether endotoxin (LPS) stimulated Langerhans cells and macrophages (Mphi; from B6 mice) provided signals to activate NKT cells. LPS up-regulated mRNA expression for IL-12p40, costimulatory molecules CD80 and CD86, NF-kappaB, and CD1d, and addition of rIFN-gamma potentiated Mphi CD1d levels. Together, these data suggest that Langerhans cell/Mphi recognition of microbial LPS regulates IL-12p40 (and CD1d) driven IFN-gamma production by NKT cells, that IFN-gamma is required to optimally activate NK cells to produce IFN-gamma, and that depletion of both NKT/NK cells results in earlier corneal perforation.

Formalin-Fixed Staphylococcus aureus Particles Prevent Allergic Sensitization in a Murine Model of Type I Allergy

Background: Bacterial infections are supposed to act counterregulatory to the development of allergen-specific Th2 immune responses. We analyzed whether administration of extracellular Staphylococcus aureus inhibited experimental sensitization against allergens. Methods: BALB/c mice were immunized with alum-adsorbed ovalbumin (OVA) together with formalin-fixed Staphylococcus particles. OVA-specific antibody production and cytokine synthesis by spleen cells was analyzed. Airway reactivity and cellular infiltration into the airways was assessed after intranasal challenge of mice with OVA. In addition, the capacity of Staphylococcus particles to modulate cytokine production by bone marrow-derived dendritic cells was analyzedin vitro. Results: Simultaneous application of OVA and Staphylococcus particles very efficiently inhibited production of specific IgE and IgG1 as well as secretion of IL-4 and IL-5 by splenocytes, while enhancing IgG2a formation and production of IFN-γ, indicating a shift from a Th2 response towards a Th1-biased response. This effect was not dependent on the expression of protein A by Staphylococcus. An enhanced frequency or activity of regulatory T cells after administration of Staphylococcus particles was not apparent. Treatment of mice with Staphylococcus particles during the sensitization phase prevented lung inflammation (airway hyperreactivity, eosinophilia) after local challenge with OVA. Culture of bone marrow-derived dendritic cells with Staphylococcus particles induced IL-12p35 and p40 mRNA expression as well as secretion of IL-12p70, and increased production of IL-10 mRNA and protein. Conclusions: Administration of formalin-fixed Staphylococcus particles induced Th1-biased immune responses and prevented allergic sensitization.

Impaired expression of Toll-like receptor 2 in nontuberculous mycobacterial lung disease

The aims of the present study were to investigate the expression of Toll-like receptor (TLR)2 on the peripheral blood monocytes of patients with nontuberculous mycobacterial (NTM) lung disease and healthy controls, and to assess the responses of these monocytes to TLR2 agonists such as Mycobacterium avium and lipoteichoic acid (LTA). Reverse transcriptase-PCR was used to analyse TLR2 mRNA expression in peripheral blood monocytes from 17 NTM patients and 10 healthy controls. mRNA and protein secretion levels were also determined for the cytokines interleukin (IL)-12 p40 and tumour necrosis factor (TNF)-alpha. Expression of TLR2 mRNA by peripheral blood monocytes after stimulation with M. avium or LTA was lower in NTM patients than in healthy controls. IL-12 p40 and TNF-alpha mRNA and cytokine secretion levels were also lower in patients than in healthy controls. Treatment with anti-TLR antibody decreased M. avium- and LTA-induced IL-12 p40 and TNF-alpha production in healthy controls, but not in NTM patients. The present results suggest that the downregulation of Toll-like receptor 2 and the resulting decreased production of interleukin-12 p40 and tumour necrosis factor-alpha following Mycobacterium avium or lipoteichoic acid stimulation may contribute to host susceptibility to nontuberculous mycobacterial lung disease.

IL-27 Synthesis Induced by TLR Ligation Critically Depends on IFN Regulatory Factor 3

IL-27 is a heterodimeric cytokine composed of EBV-induced gene 3 and p28. Produced by dendritic cells (DCs) in response to TLR ligands, IL-27 recently emerged as a key regulator of inflammatory responses. In this study, we first demonstrate that Toll/IL-1R-containing adaptor inducing IFN-beta and its associated IFN regulatory factor (IRF) 3 transcription factor are critically involved in IL-27p28 expression in mouse DCs stimulated by TLR ligands. We then show that IL-27 serum levels are dramatically reduced in IRF3(-/-) upon LPS injection, indicating a critical role for IRF3 in TLR4-mediated IL-27 production in vivo. We identified an IRF3-binding site within the IL-27p28 promoter region which is required for IL-27p28 gene activation in reporter gene assays. In human DCs, IL-27p28 mRNA was preferentially induced by Toll/IL-1R-containing adaptor inducing IFN-beta-coupled TLR ligands and following CMV infection. Furthermore, chromatin immunoprecipitation studies demonstrate that IRF3 is recruited to the endogenous p28 promoter in TLR4-stimulated human DCs. We conclude that IRF3 activation is a master switch for IL-27 synthesis.