Epithelial p38α Controls Immune Cell Recruitment in the Colonic Mucosa

Intestinal epithelial cells (IECs) compose the first barrier against microorganisms in the gastrointestinal tract. Although the NF-κB pathway in IECs was recently shown to be essential for epithelial integrity and intestinal immune homeostasis, the roles of other inflammatory signaling pathways in immune responses in IECs are still largely unknown. Here we show that p38α in IECs is critical for chemokine expression, subsequent immune cell recruitment into the intestinal mucosa, and clearance of the infected pathogen. Mice with p38α deletion in IECs suffer from a sustained bacterial burden after inoculation with Citrobacter rodentium. These animals are normal in epithelial integrity and immune cell function, but fail to recruit CD4+ T cells into colonic mucosal lesions. The expression of chemokines in IECs is impaired, which appears to be responsible for the impaired T cell recruitment. Thus, p38α in IECs contributes to the host immune responses against enteric bacteria by the recruitment of immune cells

Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function

<p>Abstract</p> <p>Background</p> <p>Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFα and IL-1β, rather than as regulatory cytokine.</p> <p>Objective</p> <p>To investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease.</p> <p>Methods</p> <p>Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects.</p> <p>Results</p> <p>The levels of the proinflammatory biomarkers TNFα and IL-1β were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p < 0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p < 0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (r_S= 0.53, p < 0.05).</p> <p>Conclusions</p> <p>In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.</p

IL-22 Production Is Regulated by IL-23 During Listeria monocytogenes Infection but Is Not Required for Bacterial Clearance or Tissue Protection

Listeria monocytogenes (LM) is a gram-positive bacterium that is a common contaminant of processed meats and dairy products. In humans, ingestion of LM can result in intracellular infection of the spleen and liver, which can ultimately lead to septicemia, meningitis, and spontaneous abortion. Interleukin (IL)-23 is a cytokine that regulates innate and adaptive immune responses by inducing the production of IL-17A, IL-17F, and IL-22. We have recently demonstrated that the IL-23/IL-17 axis is required for optimal recruitment of neutrophils to the liver, but not the spleen, during LM infection. Furthermore, these cytokines are required for the clearance of LM during systemic infection. In other infectious models, IL-22 induces the secretion of anti-microbial peptides and protects tissues from damage by preventing apoptosis. However, the role of IL-22 has not been thoroughly investigated during LM infection. In the present study, we show that LM induces the production of IL-22 in vivo. Interestingly, IL-23 is required for the production of IL-22 during primary, but not secondary, LM infection. Our findings suggest that IL-22 is not required for clearance of LM during primary or secondary infection, using both systemic and mucosal models of infection. IL-22 is also not required for the protection of LM infected spleens and livers from organ damage. Collectively, these data indicate that IL-22 produced during LM infection must play a role other than clearance of LM or protection of tissues from pathogen- or immune-mediated damage

IL-17 Expression in the Time Course of Acute Anti-Thy1 Glomerulonephritis

Background Interleukin-17 (IL-17) is a new pro-inflammatory cytokine involved in immune response and inflammatory disease. The main source of IL-17 is a subset of CD4+ T-helper cells, but is also secreted by non-immune cells. The present study analyzes expression of IL-17 in the time course of acute anti- thy1 glomerulonephritis and the role of IL-17 as a potential link between inflammation and fibrosis. Methods Anti-thy1 glomerulonephritis was induced into male Wistar rats by OX-7 antibody injection. After that, samples were taken on days 1, 5, 10 (matrix expansion phase), 15 and 20 (resolution phase). PBS-injected animals served as controls. Proteinuria and histological matrixes score served as the main markers for disease severity. In in vitro experiments, NRK-52E cells were used. For cytokine expressions, mRNA and protein levels were analyzed by utilizing RT-PCR, in situ hybridization and immunofluorescence. Results Highest IL-17 mRNA-expression (6.50-fold vs. con; p<0.05) was found on day 5 after induction of anti-thy1 glomerulonephritis along the maximum levels of proteinuria (113 ± 13 mg/d; p<0.001), histological glomerular-matrix accumulation (82%; p<0.001) and TGF-β1 (2.2-fold; p<0.05), IL-6 mRNA expression (36-fold; p<0.05). IL-17 protein expression co-localized with the endothelial cell marker PECAM in immunofluorescence. In NRK-52E cells, co-administration of TGF-β1 and IL-6 synergistically up-regulated IL-17 mRNA 4986-fold (p<0.001). Conclusions The pro-inflammatory cytokine IL-17 is up-regulated in endothelial cells during the time course of acute anti-thy1 glomerulonephritis. In vitro, NRK-52E cells secrete IL-17 under pro-fibrotic and pro-inflammatory conditions

In Vitro Effect of Porphyromonas gingivalis Methionine Gamma Lyase on Biofilm Composition and Oral Inflammatory Response

Methanethiol (methyl mercaptan) is an important contributor to oral malodour and periodontal tissue destruction. Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum are key oral microbial species that produce methanethiol via methionine gamma lyase (mgl) activity. The aim of this study was to compare an mgl knockout strain of P. gingivalis with its wild type using a 10-species biofilm co-culture model with oral keratinocytes and its effect on biofilm composition and inflammatory cytokine production. A P. gingivalis mgl knockout strain was constructed using insertion mutagenesis from wild type W50 with gas chromatographic head space analysis confirming lack of methanethiol production. 10-species biofilms consisting of Streptococcus mitis, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp polymorphum, Fusobacterium nucleatum ssp vincentii, Veillonella dispar, Actinomyces naeslundii, Prevotella intermedia and Aggregatibacter actinomycetemcomitans with either the wild type or mutant P. gingivalis were grown on Thermanox cover slips and used to stimulate oral keratinocytes (OKF6-TERT2), under anaerobic conditions for 4 and 24 hours. Biofilms were analysed by quantitative PCR with SYBR Green for changes in microbial ecology. Keratinocyte culture supernatants were analysed using a multiplex bead immunoassay for cytokines. Significant population differences were observed between mutant and wild type biofilms; V. dispar proportions increased (p&lt;0.001), whilst A. naeslundii (p&lt;0.01) and Streptococcus spp. (p&lt;0.05) decreased in mutant biofilms. Keratinocytes produced less IL-8, IL-6 and IL-1α when stimulated with the mutant biofilms compared to wild type. Lack of mgl in P. gingivalis has been shown to affect microbial ecology in vitro, giving rise to a markedly different biofilm composition, with a more pro-inflammatory cytokine response from the keratinocytes observed. A possible role for methanethiol in biofilm formation and cytokine response with subsequent effects on oral malodor and periodontitis is suggested

Prostaglandin I2 Signaling Drives Th17 Differentiation and Exacerbates Experimental Autoimmune Encephalomyelitis

BACKGROUND: Prostaglandin I(2) (PGI(2)), a lipid mediator currently used in treatment of human disease, is a critical regulator of adaptive immune responses. Although PGI(2) signaling suppressed Th1 and Th2 immune responses, the role of PGI(2) in Th17 differentiation is not known. METHODOLOGY/PRINCIPAL FINDINGS: In mouse CD4(+)CD62L(+) naïve T cell culture, the PGI(2) analogs iloprost and cicaprost increased IL-17A and IL-22 protein production and Th17 differentiation in vitro. This effect was augmented by IL-23 and was dependent on PGI(2) receptor IP signaling. In mouse bone marrow-derived CD11c(+) dendritic cells (BMDCs), PGI(2) analogs increased the ratio of IL-23/IL-12, which is correlated with increased ability of BMDCs to stimulate naïve T cells for IL-17A production. Moreover, IP knockout mice had delayed onset of a Th17-associated neurological disease, experimental autoimmune encephalomyelitis (EAE), and reduced infiltration of IL-17A-expressing mononuclear cells in the spinal cords compared to wild type mice. These results suggest that PGI(2) promotes in vivo Th17 responses. CONCLUSION: The preferential stimulation of Th17 differentiation by IP signaling may have important clinical implications as PGI(2) and its analogs are commonly used to treat human pulmonary hypertension

Early Secreted Antigen ESAT-6 of Mycobacterium tuberculosis Promotes Protective T Helper 17 Cell Responses in a Toll-Like Receptor-2-dependent Manner

Despite its relatively poor efficacy, Bacillus Calmette-Guérin (BCG) has been used as a tuberculosis (TB) vaccine since its development in 1921. BCG induces robust T helper 1 (Th1) immune responses but, for many individuals, this is not sufficient for host resistance against Mycobacterium tuberculosis (M. tb) infection. Here we provide evidence that early secreted antigenic target protein 6 (ESAT-6), expressed by the virulent M. tb strain H37Rv but not by BCG, promotes vaccine-enhancing Th17 cell responses. These activities of ESAT-6 were dependent on TLR-2/MyD88 signalling and involved IL-6 and TGF-β production by dendritic cells. Thus, animals that were previously infected with H37Rv or recombinant BCG containing the RD1 region (BCG::RD1) exhibited improved protection upon re-challenge with virulent H37Rv compared with mice previously infected with BCG or RD1-deficient H37Rv (H37RvΔRD1). However, TLR-2 knockout (TLR-2-/-) animals neither showed Th17 responses nor exhibited improved protection in response to immunization with H37Rv. Furthermore, H37Rv and BCG::RD1 infection had little effect on the expression of the anti-inflammatory microRNA-146a (miR146a) in dendritic cells (DCs), whereas BCG and H37RvΔRD1 profoundly induced its expression in DCs. Consistent with these findings, ESAT-6 had no effect on miR146a expression in uninfected DCs, but dramatically inhibited its upregulation in BCG-infected or LPS-treated DCs. Collectively, our findings indicate that, in addition to Th1 immunity induced by BCG, RD1/ESAT-6-induced Th17 immune responses are essential for optimal vaccine efficacy

Increased Frequencies of Th22 Cells as well as Th17 Cells in the Peripheral Blood of Patients with Ankylosing Spondylitis and Rheumatoid Arthritis

<div><h3>Background</h3><p>T-helper (Th) 22 is involved in the pathogenesis of inflammatory diseases. The roles of Th22 cells in the pathophysiological of ankylosing spondylitis (AS) and rheumatoid arthritis (RA) remain unsettled. So we examined the frequencies of Th22 cells, Th17 cells and Th1 cells in peripheral blood (PB) from patients with AS and patients with RA compared with both healthy controls as well as patients with osteoarthritis.</p> <h3>Design and Methods</h3><p>We studied 32 AS patients, 20 RA patients, 10 OA patients and 20 healthy controls. The expression of IL-22, IL-17 and IFN-γ were examined in AS, RA, OA patients and healthy controls by flow cytometry. Plasma IL-22 and IL-17 levels were examined by enzyme-linked immunosorbent assay.</p> <h3>Results</h3><p>Th22 cells, Th17 cells and interleukin-22 were significantly elevated in AS and RA patients compared with OA patients and healthy controls. Moreover, Th22 cells showed positive correlation with Th17 cells as well as interleukin-22 in AS and RA patients. However, positive correlation between IL-22 and Th17 cells was only found in AS patients not in RA patients. In addition, the percentages of both Th22 cells and Th17 cells correlated positively with disease activity only in RA patients not in AS patients.</p> <h3>Conclusions</h3><p>The frequencies of both Th22 cells and Th17 cells were elevated in PB from patients with AS and patients with RA. These findings suggest that Th22 cells and Th17 cells may be implicated in the pathogenesis of AS and RA, and Th22 cells and Th17 cells may be reasonable cellular targets for therapeutic intervention.</p> </div

Role of IL-1 Beta in the Development of Human TH17 Cells: Lesson from NLPR3 Mutated Patients

T helper 17 cells (T(H)-17) represent a lineage of effector T cells critical in host defence and autoimmunity. In both mouse and human IL-1β has been indicated as a key cytokine for the commitment to T(H)-17 cells. Cryopyrin-associated periodic syndromes (CAPS) are a group of inflammatory diseases associated with mutations of the NLRP3 gene encoding the inflammasome component cryopyrin. In this work we asked whether the deregulated secretion of IL-1β secondary to mutations characterizing these patients could affect the IL-23/IL-17 axis.A total of 11 CAPS, 26 systemic onset juvenile idiopathic arthritis (SoJIA) patients and 20 healthy controls were analyzed. Serum levels of IL-17 and IL-6 serum were assessed by ELISA assay. Frequency of T(H)17 cells was quantified upon staphylococcus enterotoxin B (SEB) stimulation. Secretion of IL-1β, IL-23 and IL-6 by monocyte derived dendritic cells (MoDCs), were quantified by ELISA assay. A total of 8 CAPS and 11 SoJIA patients were also analysed before and after treatment with IL-1β blockade. Untreated CAPS patients showed significantly increased IL-17 serum levels as well as a higher frequency of T(H)17 compared to control subjects. On the contrary, SoJIA patients displayed a frequency of T(H)17 similar to normal donors, but were found to have significantly increased serum level of IL-6 when compared to CAPS patients or healthy donors. Remarkably, decreased IL-17 serum levels and T(H)17 frequency were observed in CAPS patients following in vivo IL-1β blockade. On the same line, MoDCs from CAPS patients exhibited enhanced secretion of IL-1β and IL-23 upon TLRs stimulation, with a reduction after anti-IL-1 treatment.These findings further support the central role of IL-1β in the differentiation of T(H)17 in human inflammatory conditions