Rafoxanide negatively modulates STAT3 and NF-κB activity and inflammation-associated colon tumorigenesis.

In the colorectal cancer (CRC) niche, the transcription factors signal transducer and activator of transcription 3 (STAT3) and nuclear factor-κB (NF-κB) are hyperactivated in both malignant cells and tumor-infiltrating leukocytes (TILs) and cooperate to maintain cancer cell proliferation/survival and drive protumor inflammation. Through drug repositioning studies, the anthelmintic drug rafoxanide has recently emerged as a potent and selective antitumor molecule for different types of cancer, including CRC. Here, we investigate whether rafoxanide could negatively modulate STAT3/NF-κB and inflammation-associated CRC. The antineoplastic effect of rafoxanide was explored in a murine model of CRC resembling colitis-associated disease. Cell proliferation and/or STAT3/NF-κB activation were evaluated in colon tissues taken from mice with colitis-associated CRC, human CRC cells, and CRC patient-derived explants and organoids after treatment with rafoxanide. The STAT3/NF-κB activation and cytokine production/secretion were assessed in TILs isolated from CRC specimens and treated with rafoxanide. Finally, we investigated the effects of TIL-derived supernatants cultured with or without rafoxanide on CRC cell proliferation and STAT3/NF-κB activation. The results showed that rafoxanide restrains STAT3/NF-κB activation and inflammation-associated colon tumorigenesis in vivo without apparent effects on normal intestinal cells. Rafoxanide markedly reduces STAT3/NF-κB activation in cultured CRC cells, CRC-derived explants/organoids, and TILs. Finally, rafoxanide treatment impairs the ability of TILs to produce protumor cytokines and promote CRC cell proliferation. We report the novel observation that rafoxanide negatively affects STAT3/NF-κB oncogenic activity at multiple levels in the CRC microenvironment. Our data suggest that rafoxanide could potentially be deployed as an anticancer drug in inflammation-associated CRC.

TGF-ß1 signaling and Smad7 control T-cell responses in health and immune-mediated disorders.

Transforming growth factor (TGF)-ß1, a member of the TGF-ß superfamily, is produced by many immune and nonimmune cells and has pleiotropic effects on both innate and adaptive immunity, especially in the control of T-cell differentiation and function. Consistently, loss of TGF-ß1 function is associated with exacerbated T-cell-dependent inflammatory responses that culminate in pathological processes in allergic and immune-mediated diseases. In this review, we highlight the roles of TGF-ß1 in immunity, focusing mainly on its ability to promote differentiation of regulatory T cells, T helper (Th)-17, and Th9 cells, thus contributing to amplifying or restricting T-cell responses in health and human diseases (e.g., inflammatory bowel diseases, type 1 diabetes, asthma, and MS). In addition, we discuss the involvement of Smad7, an inhibitor of TGF-ß1 signaling, in immune-mediated disorders (e.g., psoriasis, rheumatoid arthritis, MS, and inflammatory bowel diseases), as well as the discordant results of clinical trials with mongersen, an oral pharmaceutical compound containing a Smad7 antisense oligonucleotide, in patients with Crohn's disease. Further work is needed to ascertain the reasons for such a discrepancy as well as to identify better candidates for treatment with Smad7 inhibitors.

Aryl Hydrocarbon Receptor Signalling in the Control of Gut Inflammation.

Aryl hydrocarbon receptor (AHR), a transcription factor activated by many natural and synthetic ligands, represents an important mediator of the interplay between the environment and the host's immune responses. In a healthy gut, AHR activation promotes tolerogenic signals, which help maintain mucosal homeostasis. AHR expression is defective in the inflamed gut of patients with inflammatory bowel diseases (IBD), where decreased AHR signaling is supposed to contribute to amplifying the gut tissue's destructive immune-inflammatory responses. We here review the evidence supporting the role of AHR in controlling the "physiological" intestinal inflammation and summarize the data about the therapeutic effects of AHR activators, both in preclinical mouse models of colitis and in patients with IBD.

Albendazole negatively regulates keratinocyte proliferation.

BACKGROUND: Increased keratinocyte proliferation occurs in the skin of psoriatic patients and is supposed to play a role in the pathogenesis of this disorder. Compounds interfering with keratinocyte proliferation could be useful in the management of psoriatic patients. AIM: To investigate whether albendazole, an anti-helmintic drug that regulates epithelial cell function in various systems, inhibits keratinocyte proliferation in models of psoriasis. METHODS: Aldara-treated mice received daily topical application of albendazole. Keratinocyte proliferation and keratin (K) 6 and K16 expression were evaluated by immunohistochemistry and Western blotting and inflammatory cells/mediators were analysed by immunohistochemistry and real-time PCR. In human keratinocytes (HEKa and HaCaT) treated with albendazole, cell cycle and proliferation, keratins and cell cycle-associated factors were evaluated by flow cytometry, colorimetric assay and Western blotting respectively. RESULTS: Aldara-treated mice given albendazole exhibited reduced epidermal thickness, decreased number of proliferating keratinocytes and K6/K16 expression. Reduction of CD3- and Ly6G-positive cells in the skin of albendazole-treated mice associated with inhibition of IL-6, TNF-α, IL-1ß, IL-17A, IL-36, CCL17, CXCL1, CXCL2 and CXCL5 expression. Treatment of keratinocytes with albendazole reduced K6/K16 expression and reversibly inhibited cell growth by promoting accumulation of cells in S-phase. This phenomenon was accompanied by down-regulation of CDC25A, a phosphatase regulating progression of cell cycle through S-phase, and PKR-dependent hyper-phosphorylation of eIF2α, an inhibitor of CDC25 translation. In Aldara-treated mice, albendazole activated PKR, enhanced eIF2α phosphorylation and reduced CDC25A expression. CONCLUSIONS: Data show that albendazole inhibits keratinocyte proliferation and exerts therapeutic effect in a murine model of psoriasis.

Effect of chemical modulation of toll-like receptor 4 in an animal model of ulcerative colitis.

PURPOSE: The partial ineffectiveness and side effects of inflammatory bowel disease (IBD) current therapies drive basic research to look for new therapeutic target in order to develop new drug lead. Considering the pivotal role played by toll-like receptors (TLRs) in gut inflammation, we evaluate here the therapeutic effect of the synthetic glycolipid TLR4 antagonist FP7. METHODS: The anti-inflammatory effect of FP7, active as TLR4 antagonist, was evaluated on peripheral blood mononuclear cells (PBMCs) and lamina propria mononuclear cells (LPMCs) isolated from IBD patients, and in a mouse model of ulcerative colitis. RESULTS: FP7 strongly reduced the inflammatory responses induced by lipopolysaccharide (LPS) in vitro, due to its capacity to compete with LPS for the binding of TLR4/MD-2 receptor complex thus inhibiting both the MyD88- and TRIF-dependent inflammatory pathways. Colitic mice treated with FP7 exhibit reduced colonic inflammation and decreased levels of pro-inflammatory cytokines. CONCLUSIONS: This study suggests that TLR4 chemical modulation can be an effective therapeutic approach to IBD. The selectivity of FP7 on TLR4 makes this molecule a promising drug lead for new small molecules-based treatments.

Inhibiting Oxidative Phosphorylation In Vivo Restrains Th17 Effector Responses and Ameliorates Murine Colitis.

Integration of signaling and metabolic pathways enables and sustains lymphocyte function. Whereas metabolic changes occurring during T cell activation are well characterized, the metabolic demands of differentiated T lymphocytes are largely unexplored. In this study, we defined the bioenergetics of Th17 effector cells generated in vivo. These cells depend on oxidative phosphorylation (OXPHOS) for energy and cytokine production. Mechanistically, the essential role of OXPHOS in Th17 cells results from their limited capacity to increase glycolysis in response to metabolic stresses. This metabolic program is observed in mouse and human Th17 cells, including those isolated from Crohn disease patients, and it is linked to disease, as inhibiting OXPHOS reduces the severity of murine colitis and psoriasis. These studies highlight the importance of analyzing metabolism in effector lymphocytes within in vivo inflammatory contexts and suggest a therapeutic role for manipulating OXPHOS in Th17-driven diseases.

Metformin inhibits inflammatory signals in the gut by controlling AMPK and p38 MAP kinase activation.

Metformin, a hypoglycemic drug used for treatment of type 2 diabetes, regulates inflammatory pathways. By using several models of intestinal inflammation, we examined whether metformin exerts anti-inflammatory effects and investigated the basic mechanism by which metformin blocks pathologic signals. Colitic mice given metformin exhibited less colonic inflammation and increased expression of active AMP-activated protein kinase, a mediator of the metabolic effects of metformin, in both epithelial and lamina propria compartments. Pharmacological inhibition of AMP-activated protein kinase reduced but did not prevent metformin-induced therapeutic effect as well as treatment of colitic mice with a pharmacological activator of AMP-activated protein kinase attenuated but did not resolve colitis. These data suggest that the anti-inflammatory effect of metformin relies on the control of additional pathways other than AMP-activated protein kinase. Indeed, metformin down-regulated p38 MAP kinase activation in colitic mice through an AMP-activated protein kinase-independent mechanism. Expression of active form of AMP-activated protein kinase was reduced in inflammatory bowel disease patients and treatment of mucosal cells of such patients with metformin enhanced AMP-activated protein kinase activation and reduced p38 MAP kinase activation, thereby inhibiting interleukin-6 expression. Our findings indicate that metformin is a good candidate for inhibiting pathological inflammation in the gut.

Aryl hydrocarbon receptor-driven signals inhibit collagen synthesis in the gut.

Fibrostrictures (FS) are a major complication of Crohn's disease (CD). Pathogenesis of FS is not fully understood, but activation of fibroblasts and excessive collagen deposition are crucial in the development of FS. Here, we investigated the role of aryl hydrocarbon receptor (AhR) in intestinal fibrosis. AhR RNA and protein expression were evaluated in intestinal fibroblasts of CD patients and controls. CD fibroblasts were stimulated with TGF-ß1 or TNF-α in the presence or absence of the AhR activator Ficz, an AhR antagonist CH223191, or a specific AhR-silencing RNA. In CD fibroblasts, TGF-ß1 and TNF-α increased Col1A1, Col3A1 and α-SMA transcripts and collagen secretion and this effect was reduced by Ficz and upregulated by CH22319. TGF-ß1 or TNF-α induced activation of p38 and ERK1/2 MAP kinases was decreased by Ficz and increased by CH223191. The inhibitory effect of Ficz on Map kinase activation and collagen induction was abolished by AhR silencing. To assess the role of AhR in vivo, mice with trinitrobenzene-sulfonic-acid induced colonic fibrosis were given Ficz or CH223191. Mice given either Ficz or CH223191 produced less or more collagen respectively as compared with control mice. Our results indicate that AhR is a negative regulator of profibrotic signals in the gut.

Evidence of IL-17 producing innate lymphoid cells in peripheral blood from patients with enteropathic spondyloarthritis.

OBJECTIVES: Both the innate and the adaptive immune responses contribute to the onset of chronic inflammation in spondyloarthritis (SpA). The association between SpA and inflammatory bowel disease (IBD, enteropathic SpA-ESpA) has been largely established and suggests a shared pathophysiology. There is evidence that innate lymphoid cells (ILC) are involved in the pathogenesis of both SpA and IBD while no evidence has been reported to date on ESpA. We aimed to analyse for the first time the frequency and cytokine expression of ILC in peripheral blood from ESpA patients compared with both IBD and healthy subjects. Correlations between immunophenotyping and disease activity were also explored. METHODS: ESpA patients (n=20) were prospectively enrolled. Healthy controls (HC, n=10) and IBD patients (n=10) served as control groups. Peripheral blood Interferon (IFN)-γ and interleukin (IL)-17 expressing T and non-T cells as well as ILC subsets (ILC-1: IFN- γ +; ILC-3: IL-17+; natural killer-NK) were characterised by flowcytometry. Correlations between IL-17+ cells and SpA disease activity were analysed. RESULTS: ESpA patients showed higher levels of ROR-γ expressing non T-cells with the respect to the controls. IL-17 producing non-T cells were higher than the HC and positively correlated with IFN-γ expressing cells levels as well as with SpA disease activity. ESpA showed higher levels of ILC-1 and ILC-3 than both IBD and HC. IFN-γ expressing NK cells were higher in ESpA than HC. CONCLUSIONS: Our preliminary findings indicate that peripheral blood of ESpA patients is enriched for IL-17 expressing ILC which distinguishes the blood compartment from both IBD and HC. The increased IL-17 production by ILC indicates a novel role for ILC in ESpA.

Plasma cells in the mucosa of patients with inflammatory bowel disease produce granzyme B and possess cytotoxic activities.

In both Crohn's disease (CD) and ulcerative colitis (UC), the gut is massively infiltrated with B cells and plasma cells, but the role of these cell types in the pathogenesis of gut tissue damage remains largely unknown. Human B cells express granzyme B (GrB) when cultured with IL-21, a cytokine overproduced in CD and UC mucosa. We therefore examined whether mucosal B cells express GrB and have cytotoxic activity in inflammatory bowel disease (IBD). GrB-expressing CD19(+) and IgA(+) cells were seen in the normal intestinal mucosa, but they were significantly more frequent in both CD and UC. In contrast, only a minority of CD19(+) and IgA(+) cells expressed perforin with no difference between IBD and controls. GrB-producing CD19(+) cells expressed CD27 and were CD38(high) and CD20 negative. CD19(+) B cells from IBD patients induced HCT-116 cell death. IL-21 enhanced GrB expression in control CD19(+) B cells and increased their cytotoxic activity. These data indicate that IBD-related inflammation is marked by mucosal accumulation of cytotoxic, GrB-expressing CD19(+) and IgA(+) cells, suggesting a role for these cells in IBD-associated epithelial damage.

Interleukin-34 sustains inflammatory pathways in the gut.

IBD (inflammatory bowel disease)-related tissue damage occurs in areas which are massively infiltrated with monocytes/macrophages. These cells respond to inflammatory stimuli with enhanced production of cytokines/chemokines. In the present study, we analysed the expression and role of IL (interleukin)-34, a regulator of monocyte/macrophage differentiation, survival and function, in IBD. A significant increase in IL-34 mRNA and protein expression was seen in inflamed mucosa of patients with CD (Crohn's disease) and patients with UC (ulcerative colitis) compared with the uninvolved areas of the same patients and normal controls. IL-34 was up-regulated in LPMCs (lamina propria mononuclear cells) isolated from normal colon by TNF-α (tumour necrosis factor α) and TLR (Toll-like receptor) ligands and was down-regulated in intestinal biopsies and LPMCs of IBD patients upon treatment with infliximab. Treatment of normal LPMCs with IL-34 increased TNF-α expression in an ERK1/2 (extracellular-signal-regulated kinase 1/2)-dependent fashion and neutralization of IL-34 in IBD mucosal explants reduced TNF-α and IL-6 synthesis. In conclusion, our results indicate that IL-34 is up-regulated in IBD and suggest a role for this cytokine in sustaining the inflammatory responses in this disease.

IL-25 prevents and cures fulminant hepatitis in mice through a myeloid-derived suppressor cell-dependent mechanism.

UNLABELLED: Fulminant hepatitis (FH) is a disease characterized by massive destruction of hepatocytes with severe impairment of liver function. The pathogenesis of FH is not fully understood, but hyperactivity of T cells and macrophages with excessive production of cytokines are important hallmarks of the condition. In this study, we investigated the role of interleukin (IL)-25 in FH. IL-25 expression was evaluated in patients with FH and in livers of mice with FH induced by D-galactosamine (D-Gal) and lipopolysaccharide (LPS). Mice were treated with IL-25 before D-Gal/LPS-induced FH and before or after concanavalin A (ConA)-induced FH. Mononuclear cells were isolated from livers of mice treated with or without IL-25 and analyzed for GR1(+) CD11b(+) cells. CFSE-labeled T cells were cocultured with GR1(+) CD11b(+) cells and their proliferation was evaluated by flow cytometry. Mice were also treated with a depleting anti-GR1 antibody before IL-25 and D-Gal/LPS administration. IL-25 was constitutively expressed in mouse and human liver and down-regulated during FH. IL-25 prevented D-Gal/LPS-induced FH and this effect was associated with increased infiltration of the liver with cells coexpressing GR1 and CD11b. In vitro studies showed that GR1(+) CD11b(+) cells isolated from mice given IL-25 inhibited T-cell proliferation. Consistently, in vivo depletion of GR1(+) cells abrogated the protective effect of IL-25 in experimental D-Gal/LPS-induced FH. IL-25 was both preventive and therapeutic in ConA-induced FH. CONCLUSIONS: IL-25 expression is markedly reduced during human and experimental FH. IL-25 promotes liver accumulation of GR1(+) CD11b(+) cells with immunoregulatory properties.

SMAD7 Sustains XIAP Expression and Migration of Colorectal Carcinoma Cells.

The reorganization of the cell cytoskeleton and changes in the content of cell adhesion molecules are crucial during the metastatic spread of tumor cells. Colorectal cancer (CRC) cells express high SMAD7, a protein involved in the control of CRC cell growth. In the present study, we evaluated whether SMAD7 regulates the cytoskeleton reorganization and dynamics in CRC. Knockdown of SMAD7 with a specific antisense oligonucleotide (AS) in HCT116 and DLD1, two human CRC cell lines, reduced the migration rate and the content of F-ACTIN filaments. A gene array, real-time PCR, and Western blotting of SMAD7 AS-treated cells showed a marked down-regulation of the X-linked inhibitor of apoptosis protein (XIAP), a member of the inhibitor of apoptosis family, which has been implicated in cancer cell migration. IL-6 and IL-22, two cytokines that activate STAT3, enhanced XIAP in cancer cells, and such induction was attenuated in SMAD7-deficient cells. Finally, in human CRC, SMAD7 mRNA correlated with XIAP expression. Our data show that SMAD7 positively regulates XIAP expression and migration of CRC cells, and suggest a mechanism by which SMAD7 controls the architecture components of the CRC cell cytoskeleton.

Bromodomain-containing 4 is a positive regulator of the inflammatory cytokine response in the gut.

BACKGROUND AND AIM: Bromodomain-containing protein 4 (BRD4), one of the components of the bromodomain and extraterminal domain (BET) family, is a transcriptional and epigenetic regulator of cellular proliferation and cytokine production. In this study, we assessed whether BRD4 regulates the cytokine response in inflammatory bowel diseases (IBD). MATERIALS AND METHODS: BRD4 expression was analyzed in intestinal mucosal samples of patients with ulcerative colitis (UC), patients with Crohn's disease (CD), normal controls (CTRs), and mice with chemically-induced colitis by real-time PCR, Western blotting, and confocal microscopy. Cytokine production was evaluated in lamina propria mononuclear cells (LPMCs) of IBD patients and mucosal tissues of colitic mice treated with BRD4 inhibitors. Finally, we evaluated the effect of JQ1, an inhibitor of the BRD4 signaling pathway, on the course of murine colitis. RESULTS: BRD4 RNA and protein expression was up-regulated in the inflamed mucosa of patients with UC and patients with CD as compared to the uninvolved areas of the same patients and CTRs, and in the inflamed colon of colitic mice. Knockdown of BRD4 with a specific antisense oligonucleotide in IBD LPMCs led to reduced expression of TNF-α, IL-6, IFN-γ, and IL-17A. Administration of JQ1 to colitic mice inhibited the inflammatory cytokine response and attenuated the ongoing colitis. CONCLUSIONS: This is the first study showing the up-regulation of BRD4 in IBD and suggesting the role of such a protein in the positive control of the inflammatory cytokine response in the gut.

Targeting hepcidin in colorectal cancer triggers a TNF-dependent-gasdermin E-driven immunogenic cell death response.

Interactions between colorectal cancer (CRC) cells and the noncancerous cells in the tumor microenvironment (TME) induce mechanisms for the escape of tumor cells from immune attack. Hepcidin, a peptide that controls immune cell functions, is overproduced by CRC cells. This study aimed to evaluate whether hepcidin acts as a regulator of anti-tumor immunity in CRC. Hepcidin silencing in CRC cells was followed by enhanced TNF-driven caspase-dependent cleavage of GSDM E and death. Mice engrafted with hepcidin-deficient CT26 cells developed fewer and smaller tumors than control mice as a result of the action of tumor-infiltrating CD8+ T lymphocytes and were protected from the development of tumors in a vaccination model and exhibited long-lasting tumor protection. Additionally, hepcidin deficiency enhanced the response of mice bearing CT26-derived tumors to anti-PD-1 therapy. These results suggest that targeting hepcidin in CRC cells enhances the production of TNF thereby triggering a caspase/GSDM E-driven lytic cell death with the downstream effect of boosting a robust immune response against tumor antigens.

Tissue inhibitor of metalloproteinase-3 regulates inflammation in human and mouse intestine.

BACKGROUND & AIMS: Tissue inhibitor of metalloproteinases (TIMP)-3 is an inhibitor of matrix metalloproteinases, which regulates tissue inflammation, damage, and repair. We investigated the role of TIMP-3 in intestinal inflammation in human beings and mice. METHODS: We used real-time polymerase chain reaction and flow cytometry to measure levels of TIMP-3 in intestine samples from patients with Crohn's disease (CD) and those without (controls). We also analyzed TIMP-3 levels in lamina propria mononuclear cells (LPMCs) collected from biopsy samples of individuals with or without CD (controls) and then stimulated with transforming growth factor (TGF)-ß1, as well as in biopsy samples collected from patients with CD and then incubated with a Smad7 anti-sense oligonucleotide (knock down). LPMCs and biopsy samples from patients with CD were cultured with exogenous TIMP-3 and levels of inflammatory cytokines were measured. We evaluated the susceptibility of wild-type, TIMP-3-knockout (TIMP-3-KO), and transgenic (TIMP-3-Tg) mice to induction of colitis with 2, 4, 6-trinitrobenzene-sulfonic-acid (TNBS), and the course of colitis in recombinase-activating gene-1-null mice after transfer of wild-type or TIMP-3-KO T cells. RESULTS: Levels of TIMP-3 were reduced in intestine samples from patients with CD compared with controls. Incubation of control LPMCs with TGF-ß1 up-regulated TIMP-3; knockdown of Smad7, an inhibitor of TGF-ß1, in biopsy samples from patients with CD increased levels of TIMP-3. Exogenous TIMP-3 reduced levels of inflammatory cytokines in CD LPMCs and biopsy samples. TIMP-3-KO mice developed severe colitis after administration of TNBS, whereas TIMP-3-Tg mice were resistant to TNBS-induced colitis. Reconstitution of recombinase-activating gene-1-null mice with T cells from TIMP-3-KO mice increased the severity of colitis, compared with reconstitution with wild-type T cells. CONCLUSIONS: TIMP-3 is down-regulated in inflamed intestine of patients with CD. Its expression is regulated by TGF-ß1, and knock-down of Smad7 in intestinal tissues from patient with CD up-regulates TIMP-3. Loss or reduction of TIMP-3 in mice promotes development of colitis.

Helicobacter pylori infection associates with a mucosal downregulation of ghrelin, negative regulator of Th1-cell responses.

BACKGROUND: Helicobacter pylori (Hp)-related gastritis is characterized by a predominant T helper (Th)1/Th17 cell immunity. Ghrelin (GR) has immunoregulatory properties and inhibits experimental Th cell-dependent pathology. AIMS: To evaluate whether Hp infection associates with changes in GR expression and whether GR negatively regulates Th1/Th17 cytokines during Hp infection. METHODS: GR expression was evaluated by real-time PCR in gastric biopsies taken from Hp-infected and Hp-uninfected patients and in gastric biopsies of Hp-negative subjects cultured with or without H. pylori culture supernatant. To examine whether GR regulates Hp-induced cytokine production, H. pylori-infected gastric biopsies were stimulated with GR, and interleukin (IL)-12, interferon (IFN)-γ and IL-4 transcripts were evaluated by real-time PCR. IL-12 and IFN-γ were also analyzed in lamina propria mononuclear cells (LPMCs) extracted from Hp-infected gastric biopsies and cultured with GR. RESULTS: GR RNA transcripts were reduced in biopsies from Hp-infected patients. Treatment of Hp-negative gastric biopsies with Hp culture supernatant reduced GR RNA expression. GR dose-dependently inhibited RNA expression of IL-12 and IFN-γ but not IL-4 in ex vivo cultures of mucosal explants and in cultures of gastric LPMCs from Hp-positive patients. CONCLUSIONS: GR is downregulated in the gastric mucosa of H. pylori-infected patients. Such a defect could contribute to sustain the ongoing Th1-cell response.

IL-21 promotes skin recruitment of CD4(+) cells and drives IFN-γ-dependent epidermal hyperplasia.

Psoriasis is a chronic inflammatory disorder of the skin characterized by epidermal hyperplasia and infiltration of leukocytes into the dermis and epidermis. T cell-derived cytokines, such as IFN-γ and IL-17A, play a major role in the psoriasis-associated epidermal hyperplasia, even though factors/mechanisms that regulate the production of these cytokines are not fully understood. We have recently shown that IL-21 is synthesized in excess in psoriatic skin lesions and causes epidermal hyperplasia when injected intradermally in mice. Moreover, in the human psoriasis SCID mouse model, neutralization of IL-21 reduces both skin thickening and expression of inflammatory molecules, thus supporting the pathogenic role of IL-21 in psoriasis. However, the basic mechanism by which IL-21 promotes skin pathology remains unknown. In this study, we show that CD4(+) cells accumulate early in the dermis of IL-21-treated mice and mediate the development of epidermal hyperplasia. Indeed, IL-21 fails to induce skin damage in RAG1-deficient mice and CD4(+) cell-depleted wild-type mice. The majority of CD4(+) cells infiltrating the dermis of IL-21-treated mice express IFN-γ and, to a lesser extent, IL-17A. Studies in cytokine knockout mice show that IFN-γ, but not IL-17A, is necessary for IL-21-induced epidermal hyperplasia. Finally, we demonstrate that IFN-γ-producing CD4(+) cells infiltrating the human psoriatic plaque express IL-21R, and abrogation of IL-21 signals reduces IFN-γ expression in cultures of psoriatic CD4(+) cells. Data indicate that IL-21 induces an IFN-γ-dependent pathogenic response in vivo, thus contributing to elucidate a mechanism by which IL-21 sustains skin-damaging inflammation.

Phase I clinical trial of Smad7 knockdown using antisense oligonucleotide in patients with active Crohn's disease.

In the gut of patients with Crohn's disease (CD), high Smad7 blocks the immune-suppressive activity of transforming growth factor (TGF)-ß1, thereby contributing to amplify inflammatory signals. In vivo in mice, knockdown of Smad7 with a Smad7 antisense oligonucleotide (GED0301) attenuates experimental colitis. Here, we provide results of a phase 1 clinical, open-label, dose-escalation study of GED0301 in patients with active, steroid-dependent/resistant CD, aimed at assessing the safety and tolerability of the drug. Patients were allocated to three treatment groups receiving oral GED0301 once daily for 7 days at doses of 40, 80, or 160 mg. A total of 15 patients were enrolled. No serious adverse event was registered. GED0301 was well tolerated and no patient dropped out during the study. Twenty-five adverse events were documented in 11 patients, the majority of whom were judged to be of mild intensity and unrelated to treatment. GED0301 treatment reduced the percentage of inflammatory cytokine-expressing CCR9-positive T cells in the blood. The study shows for the first time that GED0301 is safe and well tolerated in patients with active CD.