IL-36 signaling in keratinocytes controls early IL-23 production in psoriasis-like dermatitis

IL-36R signaling plays an important role in the pathogenesis of psoriasis. We ought to assess the specific function of IL-36R in keratinocytes for the pathology of Aldara-induced psoriasis-like dermatitis. Il36r ΔK mice presenting deletion of IL-36R in keratinocytes were similarly resistant to Aldara-induced ear inflammation as Il36r -/- mice, but acanthosis was only prevented in Il36r -/- mice. FACS analysis revealed that IL-36R signaling in keratinocytes is mandatory for early neutrophil infiltration in Aldara-treated ears. RNASeq and qRT-PCR experiments demonstrated the crucial role of IL-36R signaling in keratinocytes for induction of IL-23, IL-17, and IL-22 at early time points. Taken together, our results demonstrate that IL-36R signaling in keratinocytes plays a major role in the induction of Aldara-induced psoriasis-like dermatitis by triggering early production of IL-23/IL-17/IL-22 cytokines and neutrophil infiltration.

Immunoregulatory Functions of the IL-12 Family of Cytokines in Antiviral Systems

Members of the interleukin 12 (IL-12) family have been known to be inflammatory factors since their discovery. The IL-12 family consists of IL-12, IL-23, IL-27, IL-35, and a new member, IL-39, which has recently been identified and has not yet been studied extensively. Current literature has described the mechanisms of immunity of these cytokines and potential uses for therapy and medical cures. IL-12 was found first and is effective in combatting a wide range of naturally occurring viral infections through the upregulation of various cytokines to clear the infected cells. IL-23 has an essential function in immune networks, can induce IL-17 production, and can antagonize inhibition from IL-12 in the presence of T helper (Th) 17 cells, resulting in type II IFN (IFN-γ) regulation. IL-27 has a competitive relationship to IL-35 because they both include the same subunit, the Epstein–Barr virus-induced gene3 (EBi3). This review provides a simple introduction to the IL-12 family and focuses on their functions relevant to their actions to counteract viral infections.

CNS-Specific Synthesis of Interleukin 23 Induces a Progressive Cerebellar Ataxia and the Accumulation of Both T and B Cells in the Brain: Characterization of a Novel Transgenic Mouse Model

Interleukin 23 (IL-23) is a key mediator in neuroinflammation in numerous autoimmune diseases including multiple sclerosis (MS). However, the pathophysiology of IL-23 and how it contributes to neuroinflammation is poorly defined. To further clarify the role of IL-23 in CNS inflammation, we generated a transgenic mouse model (GF-IL23) with astrocyte-targeted expression of both IL-23 subunits, IL-23p19, and IL-23p40. These GF-IL23 mice spontaneously develop a progressive ataxic phenotype, which corresponds to cerebellar tissue destruction, and inflammatory infiltrates most prominent in the subarachnoidal and perivascular space. The CNS-cytokine milieu was characterized by numerous inflammatory mediators such as IL-17a and IFNγ. However, the leukocytic infiltrates were surprisingly predominated by B cells. To further examine the impact of the CNS-specific IL-23 synthesis on an additional systemic inflammatory stimulus, we applied the LPS-induced endotoxemia model. Administration of LPS in GF-IL23 mice resulted in early and pronounced microglial activation, enhanced cytokine production and, in sharp contrast to control animals, in the formation of lymphocytic infiltrates. Our model confirms a critical role for IL-23 in the induction of inflammation in the CNS, in particular facilitating the accumulation of lymphocytes in and around the brain. Thereby, CNS-specific synthesis of IL-23 is able to induce a cascade of inflammatory cytokines leading to microglia activation, astrocytosis, and ultimately tissue damage. The presented transgenic model will be a useful tool to further dissect the role of IL-23 in neuroinflammation.

Cutting Edge: Quantitative Determination of CD40L Threshold for IL-12 and IL-23 Production from Dendritic Cells

Early secretion of IL-12 by mouse dendritic cells (DCs) instructs T cells to make IFN-γ. However, only activated, but not naive T cells are able to license DCs for IL-12 production. We hypothesized that it might be due to different levels of CD40L expression on the surface of these cells, as CD40 signals are required for IL-12 production. Using quantitative cell-free systems incorporating CD40L in lipid bilayers combined with total internal reflection fluorescence microscopy and flow cytometry, we show that as low as ∼200 CD40L molecules/μm2 in combination with IL-4 is sufficient to induce IL-12 production by DCs. Remarkably, CD40L alone is adequate to induce IL-23 secretion by DCs. Thus, although activated T cells have somewhat higher levels of CD40L, it is the combination of CD40L and the cytokines they secrete that licenses DCs and influences the effector class of the immune response.

Langerin+ DCs regulate innate IL-17 production in the oral mucosa during Candida albicans-mediated infection

The opportunistic fungal pathogen Candida albicans frequently causes diseases such as oropharyngeal candidiasis (OPC) in immunocompromised individuals. Although it is well appreciated that the cytokine IL-17 is crucial for protective immunity against OPC, the cellular source and the regulation of this cytokine during infection are still a matter of debate. Here, we directly visualized IL-17 production in the tongue of experimentally infected mice, thereby demonstrating that this key cytokine is expressed by three complementary subsets of CD90+ leukocytes: RAG-dependent αβ and γδ T cells, as well as RAG-independent ILCs. To determine the regulation of IL-17 production at the onset of OPC, we investigated in detail the myeloid compartment of the tongue and found a heterogeneous and dynamic mononuclear phagocyte (MNP) network in the infected tongue that consists of Zbtb46-Langerin- macrophages, Zbtb46+Langerin+ dendritic cells (DCs) and Ly6C+ inflammatory monocytes. Of those, the Langerin+ DC population stands out by its unique capacity to co-produce the cytokines IL-1β, IL-6 and IL-23, all of which promote IL-17 induction in response to C. albicans in the oral mucosa. The critical role of Langerin+ DCs for the innate IL-17 response was confirmed by depletion of this cellular subset in vivo, which compromised IL-17 induction during OPC. In conclusion, our work revealed key regulatory factors and their cellular sources of innate IL-17-dependent antifungal immunity in the oral mucosa.

Mesenchymal Stromal Cells and Their Extracellular Vesicles Enhance the Anti-Inflammatory Phenotype of Regulatory Macrophages by Downregulating the Production of Interleukin (IL)-23 and IL-22

Resolution-phase macrophage population orchestrates active dampening of the inflammation by secreting anti-inflammatory and proresolving products including interleukin (IL)-10 and lipid mediators (LMs). We investigated the effects of both human bone marrow-derived mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) on mature human regulatory macrophages (Mregs). The cytokines and LMs were determined from cell culture media of Mregs cultivated with MSCs and MSC-EVs. In addition, the alterations in the expression of cell surface markers and the phagocytic ability of Mregs were investigated. Our novel findings indicate that both MSC coculture and MSC-EVs downregulated the production of IL-23 and IL-22 enhancing the anti-inflammatory phenotype of Mregs and amplifying proresolving properties. The levels of prostaglandin E2 (PGE2) were substantially upregulated in MSC coculture media, which may endorse proresolving LM class switching. In addition, our results manifest, for the first time, that MSC-EVs mediate the Mreg phenotype change via PGE2. These data suggest that both human MSC and MSC-EVs may potentiate tolerance-promoting proresolving phenotype of human Mregs.

Local IL-17 Production Exerts a Protective Role in Murine Experimental Glomerulonephritis

IL-17 is a pro-inflammatory cytokine implicated in the pathogenesis of glomerulonephritis and IL-17 deficient mice are protected from nephrotoxic nephritis. However, a regulatory role for IL-17 has recently emerged. We describe a novel protective function for IL-17 in the kidney. Bone marrow chimeras were created using wild-type and IL-17 deficient mice and nephrotoxic nephritis was induced. IL-17 deficient hosts transplanted with wild-type bone marrow had worse disease by all indices compared to wild-type to wild-type bone marrow transplants (serum urea p<0.05; glomerular thrombosis p<0.05; tubular damage p<0.01), suggesting that in wild-type mice, IL-17 production by renal cells resistant to radiation is protective. IL-17 deficient mice transplanted with wild-type bone marrow also had a comparatively altered renal phenotype, with significant differences in renal cytokines (IL-10 p<0.01; IL-1β p<0.001; IL-23 p<0.01), and macrophage phenotype (expression of mannose receptor p<0.05; inducible nitric oxide synthase p<0.001). Finally we show that renal mast cells are resistant to radiation and produce IL-17, suggesting they are potential local mediators of disease protection. This is a novel role for intrinsic cells in the kidney that are radio-resistant and produce IL-17 to mediate protection in nephrotoxic nephritis. This has clinical significance as IL-17 blockade is being trialled as a therapeutic strategy in some autoimmune diseases.

Adiponectin exacerbates collagen-induced arthritis via enhancing Th17 response and prompting RANKL expression

We previously reported adiponectin (AD) is highly expressed in the inflamed synovial joint tissue and correlates closely with progressive bone erosion in Rheumatoid arthritis (RA) patients. Here, we investigate the role of adiponectin in regulating Th17 response and the expression of receptor activator of nuclear factor-κB ligand (RANKL) in mice with CIA mice by intraarticularly injection of adiponectin into knee joints on day 17, day 20 and day 23 post first collagen immunization. The increased adiponectin expression was found in inflamed joint tissue of collagen-induced arthritis (CIA) mice. Adiponectin injection resulted in an earlier onset of arthritis, an aggravated arthritic progression, more severe synovial hyperplasia, bone erosion and osteoporosis in CIA mice. CD4(+)IL-17(+) Th17 cells, IL-17 mRNA and RANKL mRNA expression were markedly increased in the joint tissue of adiponectin treated CIA mice. Moreover, adiponectin treatment markedly enhanced Th17 cell generation from naive CD4(+) T cells in vitro, which accompanied by the high expression of Th17 transcription factor ROR-γt, and Th17 cytokine genes included IL-22 and IL-23. This study reveals a novel effect of adiponectin in exacerbating CIA progression by enhancing Th17 cell response and RANKL expression.

Lymphotoxin beta receptor signaling limits mucosal damage through driving IL-23 production by epithelial cells

The immune mechanisms regulating epithelial cell repair after injury remain poorly defined. We demonstrate here that lymphotoxin beta receptor (LTβR) signaling in intestinal epithelial cells promotes self-repair after mucosal damage. Using a conditional gene-targeted approach, we demonstrate that LTβR signaling in intestinal epithelial cells is essential for epithelial interleukin-23 (IL-23) production and protection against epithelial injury. We further show that epithelial-derived IL-23 promotes mucosal wound healing by inducing the IL-22-mediated proliferation and survival of epithelial cells and mucus production. Additionally, we identified CD4(-)CCR6(+)T-bet(-) RAR-related orphan receptor gamma t (RORγt)(+) lymphoid tissue inducer cells as the main producers of protective IL-22 after epithelial damage. Thus, our results reveal a novel role for LTβR signaling in epithelial cells in the regulation of intestinal epithelial cell homeostasis to limit mucosal damage.

Inflammatory conditions distinctively alter immunological functions of Langerhans-like cells and dendritic cells in vitro

The specific function of human skin-resident dendritic cell (DC) subsets in the regulation of immunity or tolerance is still a matter of debate. Langerhans cells (LC) induce anti-viral immune responses but, conversely to dermal DC, maintain tolerance to bacteria. However, the definite function of epidermal LC and cutaneous DC appears even more complex under inflammatory conditions. Here we investigated the immune responses of human immature monocyte-derived DC (MoDC) and LC-like cells (MoLC) upon stimulation with different Toll-like receptor ligands in the presence or absence of pro-inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). In MoDC, bacterial antigens selectively up-regulated CD83 and CD86 expression and induced the release of T helper type 1 (Th1) and Th17 cytokines and led to a higher CCR7-dependent migratory capacity compared with a low responsiveness of MoLC. Importantly, MoLC activation with lipopolysaccharide under inflammatory conditions strongly enhanced a phenotypically mature state, increased IL-12p70, IL-23 and IL-6 production and Th1 cytokine secretion by CD4(+) T cells. Treatment with poly(I:C) specifically up-regulated surface expression of co-stimulatory molecules and increased release of IL-12p70 in MoLC and co-stimulation with TNF-α and IL-1β further elevated Th1 and Th17 cytokine production. Poly(I:C)-induced up-regulation of type I interferon mRNA levels in MoLC and MoDC was Toll-like receptor 3-dependent but not, or only weakly, modulated by pro-inflammatory cytokines. Our results indicate that inflammatory conditions greatly facilitate recognition of bacteria by MoLC. Furthermore, we suggest a critical involvement of both subsets in innate defence against viruses, whereas inflammatory skin environments additionally favour MoLC as potent inducers of Th1 and Th17 cytokines.

The chemokine receptor CXCR6 controls the functional topography of interleukin-22 producing intestinal innate lymphoid cells

Interleukin-22 (IL-22) plays a critical role in mucosal defense, although the molecular mechanisms that ensure IL-22 tissue distribution remain poorly understood. We show that the CXCL16-CXCR6 chemokine-chemokine receptor axis regulated group 3 innate lymphoid cell (ILC3) diversity and function. CXCL16 was constitutively expressed by CX3CR1(+) intestinal dendritic cells (DCs) and coexpressed with IL-23 after Citrobacter rodentium infection. Intestinal ILC3s expressed CXCR6 and its ablation generated a selective loss of the NKp46(+) ILC3 subset, a depletion of intestinal IL-22, and the inability to control C. rodentium infection. CD4(+) ILC3s were unaffected by CXCR6 deficiency and remained clustered within lymphoid follicles. In contrast, the lamina propria of Cxcr6(-/-) mice was devoid of ILC3s. The loss of ILC3-dependent IL-22 epithelial stimulation reduced antimicrobial peptide expression that explained the sensitivity of Cxcr6(-/-) mice to C. rodentium. Our results delineate a critical CXCL16-CXCR6 crosstalk that coordinates the intestinal topography of IL-22 secretion required for mucosal defense.

The necroptosis adaptor RIPK3 promotes injury-induced cytokine expression and tissue repair

Programmed necrosis or necroptosis is an inflammatory form of cell death that critically requires the receptor-interacting protein kinase 3 (RIPK3). Here we showed that RIPK3 controls a separate, necrosis-independent pathway of inflammation by regulating cytokine expression in dendritic cells (DCs). Ripk3(-/-) bone-marrow-derived dendritic cells (BMDCs) were highly defective in lipopolysaccharide (LPS)-induced expression of inflammatory cytokines. These effects were caused by impaired NF-κB subunit RelB and p50 activation and by impaired caspase 1-mediated processing of interleukin-1β (IL-1β). This DC-specific function of RIPK3 was critical for injury-induced inflammation and tissue repair in response to dextran sodium sulfate (DSS). Ripk3(-/-) mice exhibited an impaired axis of injury-induced IL-1β, IL-23, and IL-22 cytokine cascade, which was partially corrected by adoptive transfer of wild-type DCs, but not Ripk3(-/-) DCs. These results reveal an unexpected function of RIPK3 in NF-κB activation, DC biology, innate inflammatory-cytokine expression, and injury-induced tissue repair.

Amygdalin analogues inhibit IFN-γ signalling and reduce the inflammatory response in human epidermal keratinocytes

Peptide T (PT), an octapeptide fragment located in the V2 region of the HIV-1 gp120-coating protein, appears to be beneficial in the treatment of psoriasis. Our previous investigations suggest that keratinocytes play a key role in conditioning the therapeutic effects of PT in psoriasis. The aim of this study was to explore the effects of PT and the peptidomimetic natural products, Dhurrin and Prunasin, on the expression of the IL-6, IL-8, IL-23, HSP70 and ICAM-1 on IFN-γ and TNF-α-NHEK activated cells. Moreover, we analysed the interference of PT and its analogues through STAT-3 activation. Our results show that the analogues tested exhibit the beneficial biological effects of PT, suggesting the primary role of keratinocytes upon which PT and the peptidomimetics act directly, by reducing proinflammatory responses. Its reduction appears to be important for therapeutic approach in psoriasis pathogenesis.

Nociceptive sensory neurons drive interleukin-23-mediated psoriasiform skin inflammation

The skin has a dual function as a barrier and a sensory interface between the body and the environment. To protect against invading pathogens, the skin harbours specialized immune cells, including dermal dendritic cells (DDCs) and interleukin (IL)-17-producing γδ T (γδT17) cells, the aberrant activation of which by IL-23 can provoke psoriasis-like inflammation. The skin is also innervated by a meshwork of peripheral nerves consisting of relatively sparse autonomic and abundant sensory fibres. Interactions between the autonomic nervous system and immune cells in lymphoid organs are known to contribute to systemic immunity, but how peripheral nerves regulate cutaneous immune responses remains unclear. We exposed the skin of mice to imiquimod, which induces IL-23-dependent psoriasis-like inflammation. Here we show that a subset of sensory neurons expressing the ion channels TRPV1 and Nav1.8 is essential to drive this inflammatory response. Imaging of intact skin revealed that a large fraction of DDCs, the principal source of IL-23, is in close contact with these nociceptors. Upon selective pharmacological or genetic ablation of nociceptors, DDCs failed to produce IL-23 in imiquimod-exposed skin. Consequently, the local production of IL-23-dependent inflammatory cytokines by dermal γδT17 cells and the subsequent recruitment of inflammatory cells to the skin were markedly reduced. Intradermal injection of IL-23 bypassed the requirement for nociceptor communication with DDCs and restored the inflammatory response. These findings indicate that TRPV1(+)Nav1.8(+) nociceptors, by interacting with DDCs, regulate the IL-23/IL-17 pathway and control cutaneous immune responses.

Phosphorylated STAT3 and PD-1 regulate IL-17 production and IL-23 receptor expression in Mycobacterium tuberculosis infection

We studied the factors that regulate IL-23 receptor expression and IL-17 production in human tuberculosis infection. Mycobacterium tuberculosis (M. tb)-stimulated CD4(+) T cells from tuberculosis patients secreted less IL-17 than did CD4(+) T cells from healthy tuberculin reactors (PPD(+) ). M. tb-cultured monocytes from tuberculosis patients and PPD(+) donors expressed equal amounts of IL-23p19 mRNA and protein, suggesting that reduced IL-23 production is not responsible for decreased IL-17 production by tuberculosis patients. Freshly isolated and M. tb-stimulated CD4(+) T cells from tuberculosis patients had reduced IL-23 receptor and phosphorylated STAT3 (pSTAT3) expression, compared with cells from PPD(+) donors. STAT3 siRNA reduced IL-23 receptor expression and IL-17 production by CD4(+) T cells from PPD(+) donors. Tuberculosis patients had increased numbers of PD-1(+) T cells compared with healthy PPD(+) individuals. Anti-PD-1 antibody enhanced pSTAT3 and IL-23R expression and IL-17 production by M. tb-cultured CD4(+) T cells of tuberculosis patients. Anti-tuberculosis therapy decreased PD-1 expression, increased IL-17 and IFN-γ production and pSTAT3 and IL-23R expression. These findings demonstrate that increased PD-1 expression and decreased pSTAT3 expression reduce IL-23 receptor expression and IL-17 production by CD4(+) T cells of tuberculosis patients.

Lymphotoxin organizes contributions to host defense and metabolic illness from innate lymphoid cells

The lymphotoxin (LT)-pathway is a unique constituent branch of the Tumor Necrosis Superfamily (TNFSF). Use of LT is a critical mechanism by which fetal innate lymphoid cells regulate lymphoid organogenesis. Within recent years, adult innate lymphoid cells have been discovered to utilize this same pathway to regulate IL-22 and IL-23 production for host defense. Notably, genetic studies have linked polymorphisms in the genes encoding LTα to several phenotypes contributing to metabolic syndrome. The role of the LT-pathway may lay the foundation for a bridge between host immune response, microbiota, and metabolic syndrome. The contribution of the LT-pathway to innate lymphoid cell function and metabolic syndrome will be visited in this review.

Intestinal intraepithelial lymphocyte-enterocyte crosstalk regulates production of bactericidal angiogenin 4 by Paneth cells upon microbial challenge

Antimicrobial proteins influence intestinal microbial ecology and limit proliferation of pathogens, yet the regulation of their expression has only been partially elucidated. Here, we have identified a putative pathway involving epithelial cells and intestinal intraepithelial lymphocytes (iIELs) that leads to antimicrobial protein (AMP) production by Paneth cells. Mice lacking γδ iIELs (TCRδ(-/-)) express significantly reduced levels of the AMP angiogenin 4 (Ang4). These mice were also unable to up-regulate Ang4 production following oral challenge by Salmonella, leading to higher levels of mucosal invasion compared to their wild type counterparts during the first 2 hours post-challenge. The transfer of γδ iIELs from wild type (WT) mice to TCRδ(-/-) mice restored Ang4 production and Salmonella invasion levels were reduced to those obtained in WT mice. The ability to restore Ang4 production in TCRδ(-/-) mice was shown to be restricted to γδ iIELs expressing Vγ7-encoded TCRs. Using a novel intestinal crypt co-culture system we identified a putative pathway of Ang4 production initiated by exposure to Salmonella, intestinal commensals or microbial antigens that induced intestinal epithelial cells to produce cytokines including IL‑23 in a TLR-mediated manner. Exposure of TCR-Vγ7(+) γδ iIELs to IL-23 promoted IL‑22 production, which triggered Paneth cells to secrete Ang4. These findings identify a novel role for γδ iIELs in mucosal defence through sensing immediate epithelial cell cytokine responses and influencing AMP production. This in turn can contribute to the maintenance of intestinal microbial homeostasis and epithelial barrier function, and limit pathogen invasion.

Galectin-3 modulates Th17 responses by regulating dendritic cell cytokines

Galectin-3 is a β-galactoside-binding animal lectin with diverse functions, including regulation of T helper (Th) 1 and Th2 responses. Current data indicate that galectin-3 expressed in dendritic cells (DCs) may be contributory. Th17 cells have emerged as critical inducers of tissue inflammation in autoimmune disease and important mediators of host defense against fungal pathogens, although little is known about galectin-3 involvement in Th17 development. We investigated the role of galectin-3 in the induction of Th17 immunity in galectin-3-deficient (gal3(-/-)) and gal3(+/+) mouse bone marrow-derived DCs. We demonstrate that intracellular galectin-3 negatively regulates Th17 polarization in response to the dectin-1 agonist curdlan (a β-glucan present on the cell wall of fungal species) and lipopolysaccharide, agents that prime DCs for Th17 differentiation. On activation of dectin-1, gal3(-/-) DCs secreted higher levels of the Th17-axis cytokine IL-23 compared with gal3(+/+) DCs and contained higher levels of activated c-Rel, an NF-κB subunit that promotes IL-23 expression. Levels of active Raf-1, a kinase that participates in downstream inhibition of c-Rel binding to the IL23A promoter, were impaired in gal3(-/-) DCs. Modulation of Th17 by galectin-3 in DCs also occurred in vivo because adoptive transfer of gal3(-/-) DCs exposed to Candida albicans conferred higher Th17 responses and protection against fungal infection. We conclude that galectin-3 suppresses Th17 responses by regulating DC cytokine production.

Tristetraprolin regulation of interleukin 23 mRNA stability prevents a spontaneous inflammatory disease

Interleukin (IL) 12 and IL23 are two related heterodimeric cytokines produced by antigen-presenting cells. The balance between these two cytokines plays a crucial role in the control of Th1/Th17 responses and autoimmune inflammation. Most studies focused on their transcriptional regulation. Herein, we explored the role of the adenine and uridine-rich element (ARE)-binding protein tristetraprolin (TTP) in influencing mRNA stability of IL12p35, IL12/23p40, and IL23p19 subunits. LPS-stimulated bone marrow-derived dendritic cells (BMDCs) from TTP(-/-) mice produced normal levels of IL12/23p40. Production of IL12p70 was modestly increased in these conditions. In contrast, we observed a strong impact of TTP on IL23 production and IL23p19 mRNA stability through several AREs in the 3' untranslated region. TTP(-/-) mice spontaneously develop an inflammatory syndrome characterized by cachexia, myeloid hyperplasia, dermatitis, and erosive arthritis. We observed IL23p19 expression within skin lesions associated with exacerbated IL17A and IL22 production by infiltrating γδ T cells and draining lymph node CD4 T cells. We demonstrate that the clinical and immunological parameters associated with TTP deficiency were completely dependent on the IL23-IL17A axis. We conclude that tight control of IL23 mRNA stability by TTP is critical to avoid severe inflammation.

[Effect of dendritic cells on the differentiation of Th1/Th17 in peripheral blood from preeclampsia patients]

OBJECTIVE

To observe the effect of dendritic cells (DCs) derived from peripheral blood monouclear cells (PBMCs) on the differentiation of Th1 and Th17 in normal pregnancy women and preeclampsia patients.

METHODS

PBMCs were obtained from 32 preeclampsia patients and 20 normal pregnancy controls, respectively. Then DCs were sorted from peripheral blood monocytes cultured in the presence of cytokines (GM-CSF, IL-4) and LPS for 8 d. The phenotypes of DCs (CD14, CD80, CD83, CD86) were detected by flow cytometry (FCM). The content of IL-23 in the supernatant was detected by ELISA. CD4(+);T lymphocytes were separated using the magnetic BD IMag Cell Separation System according to the manufacturer's instructions. Purified CD4(+);T lymphocytes were clutured with mature DCs derived from normal pregnancy women (N-DC) and IL-2, or with mature DCs derived from preeclampsia patients (P-DC) and IL-2, or with N-DC and IL-1β, IL-6, or with P-DC and IL-1β, IL-6. At 6 days after culture, CD4(+);IFN-γ(+);T(Th1) and CD4(+);IL-17(+);T(Th17) subsets were determined by FCM.

RESULTS

Compared with N-DC, P-DC expressed the higher levels of CD83, CD80, CD86 and manifestated the stronger ability of promoting the differentiation of CD4(+);T into Th1/Th17 when cultured with different cytokines (P<0.01).

CONCLUSION

The changes in phenotype and function of DCs might be related to immune imbalance and be an important reason for preeclampsia.

Nicotinic receptor alpha7 expression identifies a novel hematopoietic progenitor lineage

How inflammatory responses are mechanistically modulated by nicotinic acetylcholine receptors (nAChR), especially by receptors composed of alpha7 (α7) subunits, is poorly defined. This includes a precise definition of cells that express α7 and how these impact on innate inflammatory responses. To this aim we used mice generated through homologous recombination that express an Ires-Cre-recombinase bi-cistronic extension of the endogenous α7 gene that when crossed with a reporter mouse expressing Rosa26-LoxP (yellow fluorescent protein (YFP)) marks in the offspring those cells of the α7 cell lineage (α7^lin+). In the adult, on average 20–25 percent of the total CD45⁺ myeloid and lymphoid cells of the bone marrow (BM), blood, spleen, lymph nodes, and Peyers patches are α7^lin+, although variability between litter mates in this value is observed. This hematopoietic α7^lin+ subpopulation is also found in Sca1⁺cKit⁺ BM cells suggesting the α7 lineage is established early during hematopoiesis and the ratio remains stable in the individual thereafter as measured for at least 18 months. Both α7^lin+ and α7^lin– BM cells can reconstitute the immune system of naïve irradiated recipient mice and the α7^lin+:α7^lin– beginning ratio is stable in the recipient after reconstitution. Functionally the α7^lin+:α7^lin– lineages differ in response to LPS challenge. Most notable is the response to LPS as demonstrated by an enhanced production of IL-12/23(p40) by the α7^lin+ cells. These studies demonstrate that α7^lin+ identifies a novel subpopulation of bone marrow cells that include hematopoietic progenitor cells that can re-populate an animal’s inflammatory/immune system. These findings suggest that α7 exhibits a pleiotropic role in the hematopoietic system that includes both the direct modulation of pro-inflammatory cell composition and later in the adult the role of modulating pro-inflammatory responses that would impact upon an individual’s lifelong response to inflammation and infection.

Early IL-17 production by intrahepatic T cells is important for adaptive immune responses in viral hepatitis

This study was conducted to examine the interactions among the innate and adaptive immune components of the liver parenchyma during acute viral hepatitis. Mice were i.v. infected with a recombinant adenovirus, and within the first 24 h of infection, we found a transient but significant accumulation of IL-17 and IL-23 in the liver. In vivo neutralization of these interleukins alleviated the liver injury. Further investigations showed that IL-17 neutralization halted the intrahepatic accumulation of CTLs and Th1 cells. A majority of the IL-17-producing cells in the liver were γδ T cells. Additionally, intrahepatic IL-17(+) γδ T cells, but not the IFN-γ(+) ones, preferentially expressed IL-7Rα (CD127) on their surface, which coincided with an elevation of hepatocyte-derived IL-7 at 12 h postinfection. IL-7Rα blockade in vivo severely impeded the expansion of IL-17-producing cells after viral infection. In vitro, IL-7 synergized with IL-23 and directly stimulated IL-17 production from γδ T cells in response to TCRγδ stimulation. Finally, type I IFN (IFN-I) signaling was found to be critical for hepatic IL-7 induction. Collectively, these results showed that the IFN-I/IL-7/IL-17 cascade was important in priming T cell responses in the liver. Moreover, the highly coordinated cross talk among hepatocytes and innate and adaptive immune cells played a critical role in anti-viral immunity in hepatitis.

[Expressions and significance of IL-17 and IL-23 in intestinal mucosa of mice infected with Blastocystis hominis]

OBJECTIVE

To study the expressions of interleukin-17 (IL-17) and interleukin-23 (IL-23) in the intestinal mucosa of BABL/C mice infected with Blastocystis hominis.

METHODS

A total of 30 BABL/C mice were randomly divided into different groups: an experimental group, an immunosuppressant group and a normal group. Each mouse of the experimental group and immunosuppressant group was administered intraperieneally with dexamethasone (2 mg, gd, for 5 days) and one of the control group was given physiological saline (0.2 ml). In the experimental group, each mouse was infected with Blastocystis hominis (107 parasites per 0.5 ml) by the intragastric infusion method; in the immunosuppressant group and normal group, the mice were fed with equal physiological saline. On the fifth day post-infection, the duodenum, jejunum, ileum and colon of the mice of the 3 groups were taken out for the tissue section. The pathological changes of bowel mucosa were determined by HE staining, and the expressions of IL-17 and IL-23 in different parts of bowel mucosa were determined by immunohistochemistry assay.

RESULTS

The pathological examinations showed intestinal mucosa had various degrees of inflammatory changes. The expressions of IL-17 and IL-23 in the intestinal mucosa of the mice in the experimental group was significantly higher than those in the immunosuppressant group or normal group (both P < 0.05). The expressions of IL-17 and IL-23 in the intestinal mucosa of the mice in the immunosuppressant group were similar to those in the normal group (P > 0.05). The expression of IL-17 in the duodenum or jejunum or colon of the mice was significantly higher than that in the ileum in the experimental group (P < 0.05). The expression of IL-23 in the duodenum or jejunum of the mice was significantly higher that that in the ileum or colon in the experimental group (P < 0.05).

CONCLUSIONS

IL-17 and IL-23 are highly expressed in the intestinal mucosa of the mice infected with Blastocystis hominis. IL-23 may also be involved in the immunomodulatory effects of Blastocystis hominis infection, which plays a mutual regulatory role with IL-17.

IL-23 is pro-proliferative, epigenetically regulated and modulated by chemotherapy in non-small cell lung cancer

BACKGROUND

IL-23 is a member of the IL-6 super-family and plays key roles in cancer. Very little is currently known about the role of IL-23 in non-small cell lung cancer (NSCLC).

METHODS

RT-PCR and chromatin immunopreciptiation (ChIP) were used to examine the levels, epigenetic regulation and effects of various drugs (DNA methyltransferase inhibitors, Histone Deacetylase inhibitors and Gemcitabine) on IL-23 expression in NSCLC cells and macrophages. The effects of recombinant IL-23 protein on cellular proliferation were examined by MTT assay. Statistical analysis consisted of Student's t-test or one way analysis of variance (ANOVA) where groups in the experiment were three or more.

RESULTS

In a cohort of primary non-small cell lung cancer (NSCLC) tumours, IL-23A expression was significantly elevated in patient tumour samples (p < 0.05). IL-23A expression is epigenetically regulated through histone post-translational modifications and DNA CpG methylation. Gemcitabine, a chemotherapy drug indicated for first-line treatment of NSCLC also induced IL-23A expression. Recombinant IL-23 significantly increased cellular proliferation in NSCLC cell lines.

CONCLUSIONS

These results may therefore have important implications for treating NSCLC patients with either epigenetic targeted therapies or Gemcitabine.

TLR8 and NOD signaling synergistically induce the production of IL-1β and IL-23 in monocyte-derived DCs and enhance the expression of the feedback inhibitor SOCS2

Pattern recognition receptors (PRRs) like Toll-like receptors (TLRs) and NOD-like receptors (NLRs) are important sensors of microbial products. Although they are referred to as innate immune receptors, they make essential contributions to adaptive immune responses by activating dendritic cells (DCs). Simultaneous activation of DCs via different classes of PRRs provides a powerful tool for inducing strong immune responses. In the present study we investigate the interplay of the NLRs NOD1 and NOD2 and their crosstalk with TLR signaling in terms of DC-activation. We found strong synergistic effects upon treatment with NOD1 and NOD2 ligands combined with the TLR7/8 agonist R848. Simultaneous stimulation of monocyte-derived DCs resulted in highly increased production of IL-1β, IL-23 and SOCS2, a member of the suppressor of cytokine signaling (SOCS) family. Silencing of SOCS2 resulted in enhanced IL-23 expression, indicating that SOCS2 is involved in the regulation of TLR/NOD-dependent cytokine secretion. Finally, we demonstrate that TLR7/8-, NOD1- and NOD2-activated DCs promote CD4+ T cells to release increased amounts of IL-17. These results demonstrate that cooperative activation of DCs with NOD1 and NOD2 agonists and TLR7/8 ligands results in a synergistic release of pro-inflammatory mediators which promote the activation of IL-17-producing T cells.

Interleukin 23 production by intestinal CD103(+)CD11b(+) dendritic cells in response to bacterial flagellin enhances mucosal innate immune defense

Microbial penetration of the intestinal epithelial barrier triggers inflammatory responses that include induction of the bactericidal C-type lectin RegIIIγ. Systemic administration of flagellin, a bacterial protein that stimulates Toll-like receptor 5 (TLR5), induces epithelial expression of RegIIIγ and protects mice from intestinal colonization with antibiotic-resistant bacteria. Flagellin-induced RegIIIγ expression is IL-22 dependent, but how TLR signaling leads to IL-22 expression is incompletely defined. By using conditional depletion of lamina propria dendritic cell (LPDC) subsets, we demonstrated that CD103(+)CD11b(+) LPDCs, but not monocyte-derived CD103(-)CD11b(+) LPDCs, expressed high amounts of IL-23 after bacterial flagellin administration and drove IL-22-dependent RegIIIγ production. Maximal expression of IL-23 subunits IL-23p19 and IL-12p40 occurred within 60 min of exposure to flagellin. IL-23 subsequently induced a burst of IL-22 followed by sustained RegIIIγ expression. Thus, CD103(+)CD11b(+) LPDCs, in addition to promoting long-term tolerance to ingested antigens, also rapidly produce IL-23 in response to detection of flagellin in the lamina propria.

High dose lipopolysaccharide triggers polarization of mouse thymic Th17 cells in vitro in the presence of mature dendritic cells

Lipopolysaccharide (LPS) plays an important role in the activation of innate immune cells, leading to secretion of proinflammatory factors and bridging the adaptive immune system. Exposing total mouse thymic cells culture to LPS induced a unique expression profile of cytokines (IL-17A, IL-17F, and IL-22) and the essential ROR-γt master transcription factor, which suggested a preferential differentiation of thymocytes towards the Th17 cell phenotype. Th17-polarizing molecules (IL-23, IL-23R, IL-6, and TGF-β) and IL-17A(+)CD4(+) thymocytes were also specifically produced by the in vitro LPS-stimulation of thymic cells. Furthermore, both the expression of Th17 differentiation-related molecules and the frequency of Th17 cells were significantly up-regulated with increasing doses of LPS, as evidenced by quantitative RT-PCR and flow cytometric analysis, respectively. The expressions and frequency reached maximum levels when LPS exposure had been maintained at an extremely high concentration (100 μg/mL) for 48 h. On the other hand, depletion of thymic dendritic cells (DCs) blocked the LPS-induced polarization of thymus-derived Th17 cell lineage. Addition of bone marrow-derived DCs (BMDCs) to the purified immature CD4(+) CD62L(low) thymocytes culture recovered the switch towards Th17 cells, which synergistically prompted the cytotoxic activity of CD8(+) T cells. Taken together, our data indicates that high doses of LPS can promote the differentiation of mouse thymus-derived Th17 cells by a mechanism involving components associated with mature DCs.

Immunoproteasome-specific inhibitors and their application

Immunoproteasomes (IPs) containing the interferon-inducible subunits β1i (LMP2), β2i (MECL-1), and β5i (LMP7) alter proteasomal cleavage preference, optimise the generation of peptide ligands of MHC class I molecules, alter cytokine profile, influence T-helper cell differentiation, and play a role in T-cell survival. Small molecule inhibitors are useful tools for probing the role of the immunoproteasome in immune functions. Here, we describe different methods to characterise immunoproteasome-selective inhibitors. Thereby, we provide the methodology to analyse the specificity and cell permeability of immunoproteasome inhibitors, as well as to functionally investigate immunoproteasome inhibitors in antigen presentation.

Critical roles for LIGHT and its receptors in generating T cell-mediated immunity during Leishmania donovani infection

LIGHT (TNFSF14) is a member of the TNF superfamily involved in inflammation and defence against infection. LIGHT signals via two cell-bound receptors; herpes virus entry mediator (HVEM) and lymphotoxin-beta receptor (LTβR). We found that LIGHT is critical for control of hepatic parasite growth in mice with visceral leishmaniasis (VL) caused by infection with the protozoan parasite Leishmania donovani. LIGHT-HVEM signalling is essential for early dendritic cell IL-12/IL-23p40 production, and the generation of IFNγ- and TNF-producing T cells that control hepatic infection. However, we also discovered that LIGHT-LTβR interactions suppress anti-parasitic immunity in the liver in the first 7 days of infection by mechanisms that restrict both CD4⁺ T cell function and TNF-dependent microbicidal mechanisms. Thus, we have identified distinct roles for LIGHT in infection, and show that manipulation of interactions between LIGHT and its receptors may be used for therapeutic advantage.

Visceral leishmaniasis (VL) is a potentially fatal human disease caused by the intracellular protozoan parasites Leishmania donovani and L. infantum (chagasi). Parasites infect macrophages throughout the viscera, though the spleen and liver are the major sites of disease. VL is responsible for significant morbidity and mortality in the developing world, particularly in India, Sudan, Nepal, Bangladesh and Brazil. Because of the intrusive techniques required to analyse tissue in VL patients, our current understanding of the host immune response during VL largely derives from studies performed in genetically susceptible mice. We have discovered that mice which are unable to produce a cytokine called LIGHT have poor control of L. donovani infection in the liver, compared with wild-type control animals. In addition, we demonstrated that LIGHT has distinct roles during VL, depending on which of its two major cell-bound receptors it engages. Finally, we identified an antibody that stimulates the lymphotoxin β receptor (one of the LIGHT receptors), that can stimulate anti-parasitic activity during an established infection, thereby identifying this receptor as a therapeutic target during disease.

Pivotal role of dermal IL-17-producing γδ T cells in skin inflammation

Interleukin-23 (IL-23) and CD4(+) T helper 17 (Th17) cells are thought to be critical in psoriasis pathogenesis. Here, we report that IL-23 predominantly stimulated dermal γδ T cells to produce IL-17 that led to disease progression. Dermal γδ T cells constitutively expressed the IL-23 receptor (IL-23R) and transcriptional factor RORγt. IL-17 production from dermal γδ T cells was independent of αβ T cells. The epidermal hyperplasia and inflammation induced by IL-23 were significantly decreased in T cell receptor δ-deficient (Tcrd(-/-)) and IL-17 receptor-deficient (Il17ra(-/-)) mice but occurred normally in Tcra(-/-) mice. Imiquimod-induced skin pathology was also significantly decreased in Tcrd(-/-) mice. Perhaps further promoting disease progression, IL-23 stimulated dermal γδ T cell expansion. In psoriasis patients, γδ T cells were greatly increased in affected skin and produced large amounts of IL-17. Thus, IL-23-responsive dermal γδ T cells are the major IL-17 producers in the skin and may represent a novel target for the treatment of psoriasis.

Regulation of the development of acute hepatitis by IL-23 through IL-22 and IL-17 production

IL-23 plays a critical role in the expansion of highly proinflammatory Th17 cells secreting IL-17 and IL-22. Recently, we demonstrated that Notch signaling drives IL-22 secretion through the aryl hydrocarbon receptor (AHR) and plays a protective role in Con A-induced hepatitis. In this study, we investigated the role of IL-23 in hepatitis using IL-23p19- and IL-17-deficient mice. In WT mice, the injection of Con A induced the upregulation of various cytokines, which included IL-23, IL-22, IL-17, IFN-γ and TNF-α. In IL-23p19-deficient mice, exacerbated hepatitis was observed and serum IL-22 and IL-17 levels were greatly reduced, whereas in IL-17-deficient mice, ameliorated hepatitis was observed. The injection of exogenous IL-22 protected p19-deficient mice from hepatitis, whereas the injection of exogenous IL-23 significantly increased the serum levels of not only IL-22 but also IL-17, and less effectively protected against hepatitis in IL-17-dependent and -independent manners. Finally, it was revealed that STAT3, STAT4 and Notch contributed to the production of both the cytokines, and that the AHR was important only for IL-22 production in response to Con A and IL-23 in liver mononuclear cells. These results suggest that IL-23 plays a protective role in hepatitis through IL-22 production and also a pathological role via IL-17-dependent and -independent mechanisms.

Proinflammatory environment dictates the IL-17-producing capacity of human invariant NKT cells

CD1d-reactive invariant NKT (iNKT) cells have been implicated in a number of experimental models of human pathologies. Given the scope of their immunoregulatory activities mediated through distinct cytokine patterns, it has been proposed that this functional diversity originates from distinct iNKT subpopulations. In this study, we report that human CD161(+) iNKT cells are intrinsically endowed with the capacity to generate IL-17, but require TGF-β, IL-1β, and IL-23 to carry out this potential. IL-17-producing iNKT cells are already present in cord blood but, in contrast to peripheral blood iNKT cells, they cannot generate IFN-γ. These IL-17 producers respond to aryl hydrocarbon receptor stimulation and express IL-23 receptor and retinoic acid-related orphan receptor C, similar to conventional T helper 17 cells, from which they differ by their restricted ability to coproduce IL-22. In conclusion, IL-17 production by human iNKT cells depends on two critical parameters, namely an intrinsic program and a proinflammatory environment.

Cutting edge: crucial role of IL-1 and IL-23 in the innate IL-17 response of peripheral lymph node NK1.1- invariant NKT cells to bacteria

We have shown previously that peripheral lymph node-resident retinoic acid receptor-related orphan receptor γt(+) NK1.1(-) invariant NKT (iNKT) cells produce IL-17A independently of IL-6. In this study, we show that the concomitant presence of IL-1 and IL-23 is crucial to induce a rapid and sustained IL-17A/F and IL-22 response by these cells that requires TCR-CD1d interaction and partly relies on IL-23-mediated upregulation of IL-23R and IL-1R1 expression. We further show that IL-1 and IL-23 produced by pathogen-associated molecular pattern-stimulated dendritic cells induce this response from NK1.1(-) iNKT cells in vitro, involving mainly TLR2/4-signaling pathways. Finally, we found that IL-17A production by these cells occurs very early and transiently in vivo in response to heat-killed bacteria. Overall, our study indicates that peripheral lymph node NK1.1(-) iNKT cells could be a source of innate Th17-related cytokines during bacterial infections and supports the hypothesis that they are able to provide an efficient first line of defense against bacterial invasion.

Psoriasis and other Th17-mediated skin diseases

T helper (Th) 17 cells have crucial functions in host defense, and dysregulated Th17 responses mediate a variety of autoimmune and inflammatory conditions. Th17 cells coexpress interleukin (IL)-22, and its receptor is expressed on epidermal keratinocytes. IL-17 and IL-22 cooperatively enhance some immunological responses. A close relationship between IL-17 and the cutaneous milieu has been suggested by a number of observations. IL-17 induces the production of certain cytokines, chemokines and antimicrobial peptides by keratinocytes, and its cooperation with IL-22 has been documented. Recent findings have suggested that Th17 cells profoundly participate in the pathogenesis of certain skin disorders, in particular, psoriasis. The concept of the subsets of T cells responsible for psoriasis has been modified in the order of Th1, T cytotoxic 1, and again Thl, and Thl7 cells. IL-22 is the strongest cytokine in the keratinocyte-proliferative ability. Since IL-22 is produced by Th17 cells, they are crucial for the proliferation of keratinocytes. Furthermore, IL-22 with the help of IL-17 can induce the critical events of psoriasis, including signal transducer and activator of transcription 3 (STAT3) activation, cytokine/chemokine (IL-8 etc.) production, and antimicrobial peptide elaboration. For maintaining Th17 cells, IL-23 is required and is released from tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthetase (iNOS)-producing dendritic cells (TIP-DCs). TIP-DCs are activated via an autocrine mechanism by virtue of TNF-alpha. The above cytokine network in the pathogenesis of psoriasis has been proven by the therapeutic effectiveness of cytokine-blocking biologics. Antibodies against TNF-alpha or its soluble receptor have already been widely used in the treatment of psoriasis. The involvement of Th17 cells has also been shown in allergen-specific immune responses. The percentage of Th17 cells is increased in the peripheral blood of patients with atopic dermatitis (AD) and associated with the severity of AD. Drug eruption is another disease where Th17 cells are involved in the pathogenesis. The percentage of circulating Th17 cells are increased in drug-induced hypersensitivity syndrome, etc. Th17 cells and IL-22 are increased in patients with acute generalized exanthematous pustulosis. Since IL-17 and IL-22 cooperatively stimulate keratinocytes to produce IL-8, keratinocyte-derived IL-8 contributes to the accumulation ofneutrophils in the lesional epidermis of this drug eruption.

Src kinases are required for a balanced production of IL-12/IL-23 in human dendritic cells activated by Toll-like receptor agonists

Background

Pathogen recognition by dendritic cells (DC) is crucial for the initiation of both innate and adaptive immune responses. Activation of Toll-like Receptors (TLRs) by microbial molecular patterns leads to the maturation of DC, which present the antigen and activate T cells in secondary lymphoid tissues. Cytokine production by DC is critical for shaping the adaptive immune response by regulating T helper cell differentiation. It was previously shown by our group that Src kinases play a key role in cytokines production during TLR4 activation in human DC.

Principal Findings

In this work we investigated the role of Src kinases during different TLRs triggering in human monocyte-derived DC (MoDC). We found that Src family kinases are important for a balanced production of inflammatory cytokines by human MoDC upon stimulation of TLR3 and 8 with their respective agonists. Disruption of this equilibrium through pharmacological inhibition of Src kinases alters the DC maturation pattern. In particular, while expression of IL-12 and other inflammatory cytokines depend on Src kinases, the induction of IL-23 and co-stimulatory molecules do not. Accordingly, DC treated with Src inhibitors are not compromised in their ability to induce CD4 T cell proliferation and to promote the Th17 subset survival but are less efficient in inducing Th1 differentiation.

Conclusions

We suggest that the pharmacological modulation of DC maturation has the potential to shape the quality of the adaptive immune response and could be exploited for the treatment of inflammation-related diseases.

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.

Thymic self-reactivity selects natural interleukin 17-producing T cells that can regulate peripheral inflammation

Interleukin 17 (IL-17)-producing CD4(+) helper T cells (T(H)-17 cells) share a developmental relationship with Foxp3(+) regulatory T cells (T(reg) cells). Here we show that a T(H)-17 population differentiates in the thymus in a manner influenced by recognition of self antigen and by the cytokines IL-6 and transforming growth factor-beta (TGF-beta). Like previously described T(H)-17 cells, the T(H)-17 cells that developed in the thymus expressed the transcription factor RORgamma t and the IL-23 receptor. These cells also expressed alpha(4)beta(1) integrins and the chemokine receptor CCR6 and were recruited to the lung, gut and liver. In the liver, these cells secreted IL-22 in response to self antigen and mediated host protection during inflammation. Thus, T(H)-17 cells, like T(reg) cells, can be selected by self antigens in the thymus.

IL-17 and IL-22 are associated with protection against human kala azar caused by Leishmania donovani

IL-17 and IL-22 have been shown to increase protection against certain bacteria and fungal pathogens in experimental models. However, no human studies have demonstrated a crucial role of IL-17 and IL-22 in protection against infections. We show here that Leishmania donovani, which can cause the lethal visceral disease Kala Azar (KA), stimulates the differentiation of Th17 cells, which produce IL-17, IL-22, and IFN-gamma. Analysis of Th1, Th2, and Th17 cytokine responses by cultured PBMCs from individuals in a cohort of subjects who developed KA or were protected against KA during a severe outbreak showed that IL-17 and IL-22 were strongly and independently associated with protection against KA. Our results suggest that, along with Th1 cytokines, IL-17 and IL-22 play complementary roles in human protection against KA, and that a defect in Th17 induction may increase the risk of KA.

The influence of JNK and P38 MAPK inhibition on IL-12P40 and IL-23 production depending on IL12B promoter polymorphism

The interleukin-12p40 gene (IL12B) encodes the p40 polypeptide chain, which, together with p19, composes IL-23. A bi-allelic promoter polymorphism (IL12Bpro) located at -2703 bp of the transcription initiation site has been reported to show associations with IL-12p40 production. To elucidate the dependence of IL-12p40 and IL-23 production on IL12Bpro polymorphism in relation to MAPK signal transduction pathways, we examined the effect of JNK and p38 inhibition on the secretion of these cytokines by stimulated peripheral blood mononuclear cells (PBMC) from healthy donors with 1.1 and 1.2/2.2 IL12Bpro genotypes. Stimulation with LPS and C3bgp resulted in approximately equal IL-12p40 production from PBMC with the 1.1 and 1.2/2.2 genotypes. The inhibition of JNK and p38 before stimulation significantly upregulated IL-12p40 production by PBMC with the 1.1 genotype, but did not influence IL-12p40 production from PBMC with the 1.2/2.2 genotype. Cultures of PBMC with the 1.1 genotype produced significantly more IL-12p40 than PBMC with the 1.2/2.2 genotype after stimulation with PHA. Inhibition of p38 kinase upregulated p40 production only in cultures with the 1.1 genotype. Decreased IL-23 production was observed in C3bgp-stimulated cultures after the inhibition of p38 regardless of the genotype of the tested cells. We concluded that IL-12p40 and IL-23 expression, which is mediated by the p38 and JNK intracellular signaling pathways, is influenced by IL12Bpro polymorphism.

The pronounced Th17 profile in systemic sclerosis (SSc) together with intracellular expression of TGFbeta and IFNgamma distinguishes SSc phenotypes

BACKGROUND

Systemic sclerosis (SSc) is an autoimmune disease where controversy on Th1/Th2 balance dominates. We investigated whether the recently discovered Th17 pattern was present in SSc.

METHODOLOGY AND PRINCIPAL FINDINGS

Patients were subdivided as having limited cutaneous SSc (lcSSc, n = 12) or diffuse cutaneous SSc (dcSSc, n = 24). A further arbitrary subdivision was made between early dcSSc (n = 11) and late dcSSc (n = 13) based upon the duration of disease. As a comparator group 14 healthy controls were studied. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, CD45Ro, CD45Ra, IL-23, GITR, CD69 and intracellular expression of IL-17, TGFbeta and IFNgamma using flow cytometry. Levels of IL-17, IL-6, IL-1alpha and IL-23 were measured using Bioplex assays. SSc patients had more and more activated CD4+ cells. In addition, CD4, CD45Ro and CD45Ra cells from all SSc patients highly expressed the IL23R, which was associated with a higher IL-17 expression as well. In contrast, IFNgamma and TGFbeta were selectively up regulated in SSc subsets. In line with these observation, circulating levels of IL-17 inducing cytokines IL-6, IL-23 and IL-1alpha were increased in all or subsets of SSc patients.

CONCLUSION AND SIGNIFICANCE

The combination of IL-17, IFNgamma and TGFbeta levels in CD45Ro and CD45Ra cells from SSc patients is useful to distinguish between lSSc, ldSSc or edSSc. Blocking Th17 inducing cytokines such as IL-6 and IL-23 may provide a useful tool to intervene in the progression of SSc.

Human alveolar macrophage gene responses to Mycobacterium tuberculosis strains H37Ra and H37Rv

H37Rv and H37Ra have been widely used as models of virulent and avirulent strains, respectively, of Mycobacterium tuberculosis. Since the sequencing of H37Rv, microarrays have been used to investigate gene expression of M. tuberculosis strains under various conditions, and to compare gene expression of specific isolates of the organism. Because differences in the virulence of these organisms could also be manifest via their differential induction of host genes, we used Affymetrix Human Genome Arrays U133A and U133B to evaluate human alveolar macrophage (AM) responses to infection with H37Rv and H37Ra. H37Rv altered expression of far more genes than did H37Ra. Moreover, the genes induced by H37Rv to a greater extent than by H37Ra were predominantly associated with the development of effective immunity. H37Rv markedly increased expression of IL-23 p19, whereas neither organism significantly induced IL-12 p35 expression. Quantitative PCR confirmed that H37Rv induced significantly more AM p19 expression than did H37Ra. After low-level infection of both AM and peripheral blood monocytes (MN) with H37Rv, neither cell type produced IL-12 (by ELISA). In contrast, AM displayed significant IL-23 production in response to H37Rv, whereas MN did not. Our findings thus suggest an important role for IL-23 in human host responses to pulmonary infection with M. tuberculosis, and are consistent with epidemiologic and genetic studies that imply that H37Rv may not have unusual capacity to cause human disease.

Increased atherosclerotic lesions and Th17 in interleukin-18 deficient apolipoprotein E-knockout mice fed high-fat diet

Recent reports show T helper 17 (Th17) cells are involved in the pathogenesis of various chronic inflammatory diseases formerly categorized as Th1-mediated disorders. Interleukin-18 (IL-18) induces Th1 cells to produce interferon-gamma (IFN-gamma) which is proatherogenic, while cholesterol causes atherosclerosis and stimulates intact rat aortae to produce prostaglandin E(2) (PGE(2)), a strong regulator of IL-23 that expands Th17. We wanted to test whether Th17 is proatherogenic and whether cholesterol can induce the alternative Th17 pathway in IL-18 deficient apolipoprotein E-knockout (ApoE(-/-)) mice that have reduced Th1 cells, if they are fed high-cholesterol diet. IL-18(+/+)ApoE(-/-) and IL-18(-/-)ApoE(-/-) mice aged 5 weeks were fed high-cholesterol diet (HCD) and control littermates of IL-18(-/-)ApoE(-/-) low-cholesterol diet (LCD) for 12 weeks. At termination, cryosectioned aortic arches were stained for lesion measurement and immunohistochemistry. We found that serum cholesterol and triglyceride levels were significantly higher in IL-18(-/-)ApoE(-/-) mice on HCD and they also had significantly increased atherosclerosis compared with 18(+/+)ApoE(-/-) mice or IL-18(-/-)ApoE(-/-) mice on LCD. Increased atherosclerosis correlates with enhanced Th17-cells, IL-23-producing vascular smooth muscle cells (VSMC) and macrophages, and thin fibrous cap in lesions, the morphology indicative of unstable plaques prone to rupture. In vitro, cholesterol significantly enhances VSMCs explanted from IL-18(-/-)ApoE(-/-) but not IL-18(+/+)ApoE(-/-) aorta to produce IL-23 and homocysteine mediates secretion. This study suggests that in IL-18 deficiency, cholesterol in HCD synergize mechanistically with homocysteine to accelerate atherosclerosis via the alternative IL-23/Th17 pathway, demonstrating a new role for Th17 in atherosclerosis.

Inducible expression of functional mu opioid receptors in murine dendritic cells

Opioids are known to exert direct effects on the immune system, and the expression of functional opioid receptors has been reported on several immune cell types. Dendritic cells (DCs) are important inducers and regulators of immune responses. In this study, we investigated whether murine dendritic cells express functional mu opioid receptors (MOR). RT-PCR analysis and double immunofluorescence staining revealed the expression of MOR in activated murine dendritic cells. We also studied the dynamic expression of MOR messenger RNA in murine dendritic cells in response to different Toll-like receptor ligands. Functionally, treatment of DCs with endomorphin 1 (EM1), a specific agonist of MOR, can inhibit the forskolin-induced formation of cyclic adenosine monophosphate level in activated DCs. Moreover, EM1 treatment resulted in less activation of p38 MAPK and more activation of ERK signaling in lipopolysaccharide-stimulated DCs. Consistently, treatment of DCs with EM1 altered cytokine production by increasing IL-10 and decreasing IL-12 and IL-23. Our results suggest that MOR is inducibly expressed on activated DCs and functionally mediates EM1-induced effects on DCs. Thus, dendritic cells might be involved in crosstalk between the neuroendocrine and the immune system.

IL-23 and T(H)17-mediated inflammation in human allergic contact dermatitis

BACKGROUND

IL-17-producing T(H) (T(H)17) cells are key mediators of chronic inflammation in mice. Recent studies have implicated T(H)17-mediated inflammation in the pathogenesis of human autoimmune diseases; however, the involvement of T(H)17 cells in allergic disorders remains largely elusive.

OBJECTIVE

To investigate T(H)17-mediated inflammation in human beings with allergic contact dermatitis; in particular, the innate response of keratinocytes to contact allergen, the induction of allergen-specific T(H)17 cells, and the presence of T(H)17-related effector cells in inflamed skin.

METHODS

Human keratinocytes were stimulated with nickel in vitro followed by measurements of IL-23 and IL-12 production by quantitative PCR and ELISA. Allergen-specific memory T cells from the blood of individuals with nickel allergy and healthy controls were identified and characterized by using a short-term ex vivo assay. Nickel patch test lesions and normal skin were analyzed for the expression of T(H)17-related cells and molecules by using immunohistochemistry.

RESULTS

Keratinocytes were found to produce IL-23, but no detectable IL-12, in a response to nickel stimulation. Memory T cells isolated from peripheral blood of individuals with nickel allergy, but not healthy controls, contained T(H)17 and T(H)1 cells proliferating in response to nickel-pulsed DCs. Inflamed skin of nickel-challenged allergic individuals contained infiltrating neutrophils and cells expressing IL-17, IL-22, CCR6, and IL-22R.

CONCLUSION

Our results demonstrate the involvement of T(H)17-mediated immunopathology in human allergic contact dermatitis, including both innate and adaptive immune responses to contact allergens.

Therapeutic effects of triptolide on interleukin-10 gene-deficient mice with colitis

BACKGROUND

Triptolide, the principal active ingredient in the extract of Chinese herb Tripterygium wilfordii Hook , has both anti-inflammatory and immunomodulatory activities. However, the potential therapeutic role of triptolide in IBD was still unknown. Interleukin-10 deficient mice, a well characterized experimental model of inflammatory bowel disease, spontaneously developed a Th1 T cell-mediated colitis with many similarities to Crohn's disease. This study was designed to investigate the therapeutic effect of triptolide on the chronic colitis in IL-10-/- mice.

METHODS

Triptolide was intraperitoneally administrated every another day for 8 weeks to IL-10-/- mice. The gross and histological appearances of the colon, the level of inflammatory mediators and transcription factor activation in the colon were evaluated and compared with the control group.

RESULTS

The 8-week administration of triptolide resulted in a significant decrease in the severity of colitis, together with lower production of TNF-alpha ,IFN-gamma and IL-4 in colon. The level of serum amyloid A was decreased in triptolide-treated mice. Gene expressions of IL-12 and IL-23 in colon were also downregulated after treatment. Furthermore, administration of triptolide markedly reduced NF-small ka, CyrillicB activation in colon mucosa of IL-10-/- mice.

CONCLUSIONS

The efficacy of tritpolide treatment for the reduction of intestinal inflammation in IL-10-/- mice is a result of both anti-inflammatory and immunosuppressive activity. Triptolide holds significant potential for clinical applications for CD treatment.

Low expression of the IL-23/Th17 pathway in atopic dermatitis compared to psoriasis

The classical Th1/Th2 paradigm previously defining atopic dermatitis (AD) and psoriasis has recently been challenged with the discovery of Th17 T cells that synthesize IL-17 and IL-22. Although it is becoming evident that many Th1 diseases including psoriasis have a strong IL-17 signal, the importance of Th17 T cells in AD is still unclear. We examined and compared skin biopsies from AD and psoriasis patients by gene microarray, RT-PCR, immunohistochemistry, and immunofluorescence. We found a reduced genomic expression of IL-23, IL-17, and IFN-gamma in AD compared with psoriasis. To define the effects of IL-17 and IL-22 on keratinocytes, we performed gene array studies with cytokine-treated keratinocytes. We found lipocalin 2 and numerous other innate defense genes to be selectively induced in keratinocytes by IL-17. IFN-gamma had no effect on antimicrobial gene-expression in keratinocytes. In AD skin lesions, protein and mRNA expression of lipocalin 2 and other innate defense genes (hBD2, elafin, LL37) were reduced compared with psoriasis. Although AD has been framed by the Th1/Th2 paradigm as a Th2 polar disease, we present evidence that the IL-23/Th17 axis is largely absent, perhaps accounting for recurrent skin infections in this disease.

Invariant NKT cells produce IL-17 through IL-23-dependent and -independent pathways with potential modulation of Th17 response in collagen-induced arthritis

Invariant natural killer T (iNKT) cells play a protective role in the development of certain autoimmune diseases. However, their precise role in the pathogenesis of autoimmune arthritis remains unclear. In this study, we examined the possible contribution of iNKT cells in collagen-induced arthritis (CIA) by using iNKT cell-deficient mice (Jalpha281-/- mice). CIA in these mice was markedly suppressed and interleukin (IL)-17 production was reduced in a native type II collagen (CII)-specific T cell response. Draining lymph nodes of CII-immunized Jalpha281-/- mice contained a significantly low number of IL-17-producing T helper cells. To determine whether iNKT cells produce IL-17, we measured IL-17 by enzyme-linked immunosorbent assay in iNKT cells stimulated with the ligand, alpha-galactosylceramide (alpha-GalCer). Notably, splenocytes from Jalpha281-/- mice stimulated in this way were negative for IL-17, whereas those from C57BL/6 mice produced IL-17. Immunostaining for IL-17 in iNKT cells confirmed intracellular staining of the protein. RT-PCR analysis showed that iNKT cells expressed retinoid-related orphan receptor gammaT and IL-23 receptor. Moreover, cell sorting demonstrated that NK1.1- iNKT cells were the main producers of IL-17 compared with NK1.1+ iNKT cells. IL-17 production by iNKT cells was induced by IL-23-dependent and -independent pathways, since iNKT produced IL-17 when stimulated with either IL-23 or alpha-GalCer alone. Our findings indicate that iNKT cells are producers and activators of IL-17 via IL-23- dependent and -independent pathways, suggesting that they are key cells in the pathogenesis of CIA through IL-17.

Differences in the inducible gene expression and protein production of IL-12p40, IL-12p70 and IL-23: involvement of p38 and JNK kinase pathways

The proper balance between IL-12p40-related cytokines controls the appearance of normal and pathological Th1 immune responses. In this study, we examined the inducible IL-12p40, IL-12p35 and IL-23p19 mRNA expression and protein production in human peripheral blood mononuclear cells (PBMC) and purified monocytes, isolated from healthy donors. We investigated how JNK and p38 MAPKs inhibitors influenced IL-12p40, IL-12p70 and IL-23 production. The cytokines' quantity determination was performed by ELISA. qRT-PCR was performed for mRNA transcripts detection. All stimuli tested induced higher level of IL-12p40 and IL-12p19 mRNAs. LPS was the strongest inducer of IL-12p40 mRNA, whereas C3bgp stimulated the highest expression of IL-23p19 mRNA in human monocytes. IL-12p40 and IL-23 protein production observed was increased in the highest level after C3bgp stimulation. The inhibition of both JNK and p38 augmented IL-12p40 production. The inhibition of p38 MAPK downregulated IL-23 production and upregulated IL-12p40 production in stimulated monocytes and PBMC. These results provide evidence that in human monocytes and PBMC p38 MAP kinase activation has an opposite effect on the IL-12p40 and IL-23 expression.