B cells influence sex specificity of arthritis via myeloid suppressors and chemokines in humanized mice.

Rheumatoid arthritis (RA) occurs two times more often in women than men. B cell depletion has been shown to be efficacious in treating RA. Our previous studies suggested that antigen presentation via B cells results in a sex-specific immune response in DR4 and DR4/DQ8 mice. Here we evaluated the mechanism of efficacy of the B cell depletion in treating arthritis-susceptible DQ8 mice. The data show that arthritic DQ8 mice treated with anti-CD20 antibody in therapeutic protocols show milder disease severity in females as compared to males, which is associated with decreased antibodies to citrullinated proteins and reduced levels of IL-23 and CCL5. Treatment led to significantly increased numbers of T regulatory and monocyte-derived suppressor F4/80+Gr1hi cells in females as compared to male DQ8 mice. Our observations suggest that therapeutic strategies that target B cells may benefit females while functions of DCs might be relatively more important for men than women.

IL-23/IL-17A Dysfunction Phenotypes Inform Possible Clinical Effects from Anti-IL-17A Therapies.

Biologics that neutralize specific cytokines have improved outcomes for several immune-mediated disorders but may also increase risks for particular side effects. This article postulates potential immunologic consequences of inhibiting components of the IL-23/T-helper cell 17 pathway-the target of next-generation biologics for treating psoriasis-based on clinical phenotypes of inherent or acquired deficiencies in this pathway. Generally, downstream deficiencies (e.g., IL-17A, IL-17F) are associated with fewer disorders compared with upstream deficiencies, suggesting that selectively blocking downstream targets may result in a narrower range of side effects. However, safety of these specific inhibitions must be established in long-term studies.

Optimal clearance of Sporothrix schenckii requires an intact Th17 response in a mouse model of systemic infection.

The discovery of Th17 cells, along with many other Th cell subsets in the recent years, has expanded the Th1/Th2 paradigm that had persisted since its proposition by Mosmann in 1986. Defined by the characteristic expression of the transcription factor retinoic-related orphan receptor γt (RORγt) and production of IL-17A (IL-17), Th17 cells are powerful inducers of tissue inflammation with a recognized role against extracellular bacteria and fungi. Despite this, the interest in their study came from the pivotal role they play in the development and maintenance of major chronic inflammatory conditions such as multiple sclerosis, rheumatoid arthritis and Crohn's disease, hence they have been the target of promising new anti-Th17 therapies. Accordingly, the identification of opportunistic pathogens whose clearance relies on the Th17 response is of huge prophylactic importance. As shown here for the first time, this applies to Sporothrix schenckii, a thermo-dimorphic fungus and the causative agent of sporotrichosis. Our results show that both Th17 and Th1/Th17 mixed cells are developed during the S. schenckii systemic mice infection, which also leads to augmented production of IL-17 and IL-22. Also, by using an antibody-mediated IL-23 depletion model, we further demonstrate that optimal fungal clearance, but not survival, depends on an intact Th17 response.

Ustekinumab: moving the target from psoriasis to Crohn's disease.

Crohn's disease (CD) is an inflammatory bowel disease whose precise etiology is still unknown, and therefore a causal therapy is not yet available. Studies showing the overexpression of IL-12 and IL-23, polymorphisms in genes encoding those cytokines and their receptors and genome-wide association studies have linked Crohn's pathogenesis with IL-12/23 pathway. Ustekinumab is a novel therapeutic IgG1 kappa monoclonal antibody that modulates Th1 and Th17 function, by blocking the p40 subunit of both IL-12 and IL-23 and preventing the interaction with their receptors on T cells, natural killer cells and antigen-presenting cells with established efficacy in psoriasis. This review will mainly focus on the available evidence on the role of ustekinumab in moderate-to-severe CD. The potential role of this biologic in the armamentarium of CD therapy is discussed.

The role of aryl hydrocarbon receptor in interleukin-23-dependent restoration of interleukin-22 following ethanol exposure and burn injury.

OBJECTIVE: T-helper (Th)-17 lymphocytes play a crucial role in maintenance and regulation of gut immunity. Our laboratory has demonstrated that acute ethanol (EtOH) exposure before burn injury results in intestinal T cell suppression and enhanced bacterial translocation. BACKGROUND: To extend these studies, we examined the effects of EtOH exposure and burn injury on Th17 responses within intestinal lymphoid Peyer's patches (PP). We further investigated whether restitution of interleukin (IL)-23 enhances PP cell IL-17 and IL-22 after EtOH and burn injury. METHODS: Male mice, approximately 25 g, were gavaged with EtOH (2.9 mg/kg) before receiving an approximately 12.5% total body surface area full thickness burn. One day postinjury, PP mixed cells were cultured in the presence of plate-bound anti-CD3/soluble anti-CD28 in the presence or absence of IL-23 for 48 hours. Supernatants were harvested for IL-17 and IL-22 levels. RESULTS: When combined with EtOH intoxication, burn injury significantly decreased IL-17 and IL-22, as compared with sham injury. IL-23 treatment successfully increased levels of IL-22 but not IL-17. This restoration was prevented when PP cells were treated with CH-223191, an aryl hydrocarbon receptor inhibitor. To further delineate the mechanism of differential IL-17 and IL-22 suppression, PP cells were treated with phorbol 12-myristate 13-acetate (PMA) and ionomycin, which signal via protein kinase C (PKC) and calcium flux. Treatment with PMA and ionomycin significantly prevented the decrease in IL-17 but not IL-22 after EtOH exposure and burn injury. CONCLUSIONS: These findings suggest that IL-23-mediated restoration of IL-22 is aryl hydrocarbon receptor dependent, whereas IL-17 requires activation of protein kinase C and intracellular calcium signaling.

Specific targeting of interleukin-23p19 as effective treatment for psoriasis.

Interleukin (IL)-23 is a heterodimeric cytokine composed of a distinct p19 subunit and a p40 subunit, which it shares with IL-12. The dermatology and rheumatology communities have long surmised that anti-IL-12/23p40 antibodies suppress autoinflammatory disease owing to their effect on IL-12. The aim of this review is to bring to light new data from murine and human studies demonstrating that in fact IL-23 and its resulting Th17 pathway mediate the inflammatory cascade that induces psoriatic plaque formation. Evidence derives from lesional immunohistochemical analyses, genetic studies, and research in other autoimmune diseases. Although current IL-12/23p40 inhibitors have shown good efficacy and safety, data regarding the functional role of IL-12 in immune defense suggest that preserving this cytokine would be beneficial. To date, evidence from mouse models and preliminary data in human beings show that specifically targeting IL-23p19 may be a safer but equally efficacious treatment option.

The endocannabinoid anandamide downregulates IL-23 and IL-12 subunits in a viral model of multiple sclerosis: evidence for a cross-talk between IL-12p70/IL-23 axis and IL-10 in microglial cells.

Theiler's virus (TMEV) infection of the central nervous system (CNS) induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). The endocannabinoid system represents a novel therapeutic target for autoimmune and chronic inflammatory diseases due to its anti-inflammatory properties by regulating cytokine network. IL-12p70 and IL-23 are functionally related heterodimeric cytokines that play a crucial role in the pathogenesis of MS. In the present study we showed that the endocannabinoid anandamide (AEA) downregulated the gene expression of IL-12p70 and IL-23 forming subunits mRNAs in the spinal cord of TMEV-infected mice and ameliorated motor disturbances. This was accompanied by significant decreases on the serological levels of IL-12p70/IL-23 and more interestingly, of IL-17A. In contrast, serum levels of IL-10 resulted elevated. In addition, we studied the signalling pathways involved in the regulation of IL-12p70/IL-23 and IL-10 expression in TMEV-infected microglia and addressed the possible interactions of AEA with these pathways. AEA acted through the ERK1/2 and JNK pathways to downregulate IL-12p70 and IL-23 while upregulating IL-10. These effects were partially mediated by CB2 receptor activation. We also described an autocrine circuit of cross-talk between IL-12p70/IL-23 and IL-10, since endogenously produced IL-10 negatively regulates IL-12p70 and IL-23 cytokines in TMEV-infected microglia. This suggests that by altering the cytokine network, AEA could indirectly modify the type of immune responses within the CNS. Accordingly, pharmacological modulation of endocannabinoids might be a useful tool for treating neuroinflammatory diseases.

Endogenous PGE2 promotes the induction of human Th17 responses by fungal ß-glucan.

The interaction of PAMPs with cells of the innate immune system shapes the adaptive host response. Here, we report that ß-glucan, a major fungal PAMP purified from Candida albicans, stimulates human DCs to secrete a pro-Th17 cytokine pattern. Notably, ß-glucan induces PGE2 production, which has been shown to play a pivotal role in Th17 cell expansion. Inhibition of PGE2 synthesis or blockade of PGE2 receptors EP2 and EP4 drastically reduces IL-23 production by ß-glucan-activated DCs, suggesting that endogenous PGE2 amplifies IL-23 synthesis in response to the C. albicans PAMP. Moreover ß-glucan promotes the expansion of Th17 cells, which is strongly decreased by EP2 and EP4 receptor blockade on DCs. Our results highlight a novel role for PGE2 in the regulation of innate and adaptive immune response triggered by recognition of a prominent, highly conserved fungal PAMP such as ß-glucan.

8-methoxypsoralen plus ultraviolet A therapy acts via inhibition of the IL-23/Th17 axis and induction of Foxp3+ regulatory T cells involving CTLA4 signaling in a psoriasis-like skin disorder.

To elucidate the molecular action of 8-methoxypsoralen plus UVA (PUVA), a standard dermatological therapy, we used K5.hTGF-beta1 transgenic mice exhibiting a skin phenotype and cytokine abnormalities with strong similarities to human psoriasis. We observed that impaired function of CD4+CD25+ regulatory T cells (Tregs) and increased cytokine levels of the IL-23/Th17 pathway were responsible for the psoriatic phenotype in this mouse model. Treatment of K5.hTGF-beta1 transgenic mice with PUVA suppressed the IL-23/Th17 pathway, Th1 milieu, as well as transcription factors STAT3 and orphan nuclear receptor RORgammat. PUVA induced the Th2 pathway and IL-10-producing CD4+CD25+Foxp3+Tregs with disease-suppressive activity that was abolished by anti-CTLA4 mAb treatment. These findings were paralleled by macroscopic and microscopic clearance of the diseased murine skin. Anti-IL-17 mAb treatment also diminished the psoriatic phenotype of the mice. This indicated that both induced Tregs involving CTLA4 signaling and inhibition of the IL-23/Th17 axis are central for the therapeutic action of PUVA.

Morphine disrupts interleukin-23 (IL-23)/IL-17-mediated pulmonary mucosal host defense against Streptococcus pneumoniae infection.

Streptococcus pneumoniae is a pathogen that causes serious respiratory disease and meningitis in the immunocompromised drug abuse population. However, the precise mechanisms by which drug abuse compromises the host immune defense to pulmonary S. pneumoniae infection is not fully understood. Using a well-established murine model of opiate abuse and S. pneumoniae lung infection, we explored the influence of morphine treatment on the interleukin-23 (IL-23)/IL-17 axis and related innate immunity. Impairment of early IL-23/IL-17 production caused by morphine treatment was associated with delayed neutrophil migration and decreased pneumococcal clearance. Furthermore, morphine treatment impaired MyD88-dependent IL-23 production in alveolar macrophages and dendritic cells in response to in vitro S. pneumoniae cell infection. Moreover, morphine treatment significantly inhibited the S. pneumoniae-induced phosphorylation of interferon response factor 3 (IRF3), ATF2, and NF-kappaBp65. T-cell receptor delta (TCRdelta)-deficient mice showed a decrease in IL-17 production and a severely weakened capacity to clear lung S. pneumoniae infection. Finally, morphine treatment resulted in diminished secretion of antimicrobial proteins S100A9 and S100A8/A9 during early stages of S. pneumoniae infection. In conclusion, morphine treatment causes a dysfunction in IL-23-producing dendritic cells and macrophages and IL-17-producing gammadeltaT lymphocytes in response to S. pneumoniae lung infection. This leads to diminished release of antimicrobial S100A8/A9 proteins, compromised neutrophil recruitment, and more-severe infection.

Therapeutic effect of the potent IL-12/IL-23 inhibitor STA-5326 on experimental autoimmune uveoretinitis.

INTRODUCTION: The purpose of this study was to determine if oral administration of the interleukin (IL) 12/IL-23 inhibitor, STA-5326, is effective in experimental autoimmune uveoretinitis (EAU). METHODS: C57BL/6J mice were immunised with human interphotoreceptor retinoid binding protein peptide (IRBP 1-20). STA-5326 at a dose of either 5 mg/kg or 20 mg/kg, or vehicle alone, was orally administered once a day for six days a week from day 0 to day 14. Fundus examination was performed on day 14 and day 18 after immunisation. Mice were euthanased on day 18 and the eyes were enucleated for histopathological examination. In vivo-primed draining lymph node cells were stimulated with IRBP 1-20 and culture supernatant was harvested for assay of interferon (IFN)-gamma and IL-17 by ELISA. Intracellular expression of IFN-gamma and IL-17 in CD4+ T cells of cultured draining lymph node cells was assessed by flow cytometry. The level of IL-12 p40 in serum was examined in STA-5326-treated or vehicle-treated mice receiving immunisation. RESULTS: The level of IL-12 p40 in serum was decreased in mice treated with STA-5326. Oral administration of either 5 mg/kg or 20 mg/kg STA-5326 reduced the severity of EAU on day 14 and 18. In addition, mice treated with 20 mg/kg STA-5326 showed significantly decreased severity of EAU by histopathological analysis. Although IFN-gamma production of draining lymph node cells was increased in STA-5326-treated mice by ELISA analysis, the proportion of IFN-gamma-producing cells was not significantly altered. However, IL-17 production and the proportion of IL-17-producing cells were significantly reduced in STA-5326-treated mice. Furthermore, oral administration of STA-5326 during the effector phase reduced the severity of EAU. CONCLUSIONS: These results indicate that oral administration of the IL-12/IL-23 inhibitor STA-5326 is effective in suppressing inflammation in the EAU model, and reduces the expansion of IL-17-producing cells. STA-5326 may represent a new therapeutic modality for human refractory uveitis.

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.

Effects of glucocorticoids on STAT4 activation in human T cells are stimulus-dependent.

Glucocorticoids affect the immune system by a number of mechanisms, including modulation of cytokine production in lymphocytes. Glucocorticoids suppress T helper cell type 1 immune responses by decreasing the ability of T cells to respond to interleukin (IL)-12, a major inducer of interferon (IFN)-gamma. IFN-beta increases the expression of the anti-inflammatory cytokine IL-10 and suppresses IL-12. Signaling pathways through IFN-beta and the IL-12 receptor (IL-12R) involve activation by phosphorylation of signal transducer and activator of transcription 4 (STAT4). Our aim was to investigate the effects of dexamethasone on STAT4 activation by IFN-beta and IL-12 in human T cell blasts. We report that dexamethasone decreases IL-12-induced STAT4 phosphorylation and IFN-gamma production and enhances IFN-beta-induced STAT4 activation and IL-10 production. These effects are associated with a down-regulation of IL-12Rbeta1 expression but an up-regulation of IFN-betaR. These results indicate that the effect of glucocorticoids on the STAT4 signaling pathway depends on the stimulus activating that pathway.