23p40 Antibody Research Articles

Factors influencing the discontinuation of biologic therapies in patients with ulcerative colitis

BackgroundThe therapeutic landscape for ulcerative colitis (UC) has recently broadened to include anti-TNFα, anti-integrin, and anti-IL-12/23p40 antibody agents. These biological agents are tailored to individual patient profiles. However, some patients cease biological treatment. This study investigates factors influencing the discontinuation of biological treatment in UC patients.MethodsThis retrospective single-cohort study encompasses UC patients who commenced treatment with biological agents like infliximab, adalimumab, golimumab, vedolizumab, and ustekinumab from April 2019 to March 2022. Patients were categorized into continuation and discontinuation groups based on their one-year treatment status. Baseline characteristics were compared between the groups.ResultsOf the 116 UC patients, 102 were included in the study. Among these, 74 (72.5%) continued and 28 (27.5%) discontinued biological therapy. Discontinuation rates for infliximab, adalimumab, golimumab, vedolizumab, and ustekinumab were 33.3%, 25.0%, 50.0%, 30.2%, and 15.6%, respectively. The primary discontinuation reason was lack of efficacy (85.7%), followed by adverse events (7.1%), pregnancy (3.6%), and death (3.6%). The discontinuation group had a significantly lower rate of concomitant thiopurine compared to the continuation group (28.6% vs. 56.8%, p = 0.0132). Multivariable analysis revealed that concomitant thiopurine was independently associated with therapy continuation (p = 0.0075).ConclusionThe study indicates that concomitant thiopurine significantly correlates with the continuation of biological therapies in UC patients, underscoring the importance of concomitant thiopurine in sustaining biological therapy. Further studies are warranted to assess the efficacy of combination therapy.

COST PER REMISSION FOR MIRIKIZUMAB VS USTEKINUMAB IN THE MAINTENANCE PHASE FOR MODERATELY-TO-SEVERELY ACTIVE ULCERATIVE COLITIS TREATMENT FROM THE UNITED STATES COMMERCIAL PAYER PERSPECTIVE

Abstract BACKGROUND In phase 3 studies, mirikizumab (MIRI), an IL-23p19 antibody, demonstrated efficacy vs placebo in adult patients with moderately-to-severely active ulcerative colitis (UC). It is being developed for the United States Food and Drug Administration approval for the treatment of UC. Ustekinumab (USTE), an IL-12/23p40 antibody, is currently the most utilized second line treatment in UC patients. Physicians may prescribe MIRI in a similar placement to USTE, and payers may compare them when making formulary decisions for IL-23 inhibitors. Given the need for continued maintenance therapy to manage UC, it is of interest to evaluate the relative cost-efficiency of MIRI vs USTE. We estimated and compared the cost of MIRI vs USTE for achieving remission in one additional patient during the maintenance phase in biologic/Janus kinase inhibitor (JAKi)-experienced patients with UC. METHODS This study used a network meta-analysis (NMA) of published randomized controlled trials of maintenance phase therapy to derive the number needed to treat (NNT) for achieving clinical remission among those who responded to induction therapy. In NMA, clinical remission was defined as a total Mayo score of ≤2 points, with no individual sub-score >1. An Excel-based analytic model was developed to estimate cost per additional patient achieving clinical remission at the end of maintenance trial period. The model included the cost of maintenance therapy from a US commercial payer perspective and the NNT of achieving clinical remission for MIRI and USTE in the biologic/JAKi-experienced population. Wholesale Acquisition Cost (WAC) of USTE was taken from Micromedex Redbook. A scenario with USTE biosimilar was also considered where NNT was considered the same as USTE, but the WAC was considered 50% lower than the current WAC of USTE. RESULTS The costs per biologic/JAKi-experienced patient achieving clinical remission during the maintenance phase were $501,472 and $1,027,799 for MIRI and USTE. The lower cost per remission for MIRI in maintenance was the result of both lower relative NNT and lower anticipated WAC of MIRI compared to USTE. The scenario also resulted in a comparable cost per remission for MIRI vs a USTE biosimilar. CONCLUSION MIRI is projected to have a lower cost per remission during maintenance therapy compared to USTE. Given the need for long-term treatment for this chronic condition, MIRI appears to be a cost-efficient treatment option based on its lower NNT and anticipated acquisition cost in the maintenance phase.

Ustekinumab Decreases Circulating Th17 Cells in Ulcerative Colitis.

Objective T helper (Th) cells play a central role in the pathogenesis of ulcerative colitis (UC). The present study analyzed the changes in circulating T cells by administration of ustekinumab (UST), an interleukin-12/23p40 antibody. Methods CD4 T cells were isolated from peripheral blood at 0 and 8 weeks after UST treatment, and we analyzed the proportion of CD4 T cells by flow cytometry. Clinical information and laboratory data were obtained at 0, 8, and 16 weeks. Patients We evaluated 13 patients with UC who received UST for the induction of remission between July 2020 and August 2021. Results The median partial Mayo score improved from 4 (1-7) to 0 (0-6) (p<0.001) with UST. Among serological parameters, albumin concentrations, C-reactive protein concentrations, the sedimentation rate, and leucine-rich alpha 2 glycoprotein concentrations showed significant improvement with UST. A flow cytometric analysis of circulating CD4 T cells showed that the percentage of Th17 cells was significantly decreased by UST treatment in all patients (1.85% to 0.98%, p<0.0001). Th1 cells were significantly increased by UST treatment (9.52% to 10.4%, p<0.05), but Th2 and regulatory T cells were not significantly different. The high-Th17 subgroup had a significantly better partial Mayo score than the low-Th17 subgroup at 16 weeks after UST treatment (0 vs. 1, p=0.028). Conclusion Treatment with UST decreases circulating Th17 cells, suggesting that this change may be related to the anti-inflammatory effect of UC.

Detection of IL12/23p40 via PET Visualizes Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), which includes both Crohn disease and ulcerative colitis, is a relapsing inflammatory disease of the gastrointestinal tract. Long-term chronic inflammatory conditions elevate the patient's risk of colorectal cancer (CRC). Currently, diagnosis requires endoscopy with biopsy. This procedure is invasive and requires a bowel-preparatory regimen, adding to patient burden. Interleukin 12 (IL12) and interleukin 23 (IL23) play key roles in inflammation, especially in the pathogenesis of IBD, and are established therapeutic targets. We propose that imaging of IL12/23 and its p40 subunit in IBD via immuno-PET potentially provides a new noninvasive diagnostic approach. Methods: Our aim was to investigate the potential of immuno-PET to image inflammation in a chemically induced mouse model of colitis using dextran sodium sulfate by targeting IL12/23p40 with a 89Zr-radiolabeled anti-IL12/23p40 antibody. Results: High uptake of the IL12/23p40 immuno-PET agent was exhibited by dextran sodium sulfate-administered mice, and this uptake correlated with increased IL12/23p40 present in the sera. Competitive binding studies confirmed the specificity of the radiotracer for IL12/23p40 in the gastrointestinal tract. Conclusion: These promising results demonstrate the utility of this radiotracer as an imaging biomarker of IBD. Moreover, IL12/23p40 immuno-PET can potentially guide treatment decisions for IBD management.

P023 SZN-1326, a Wnt agonist, improved epithelial healing and ameliorated colitis in a chronic DSS model, in stark contrast to anti-TNF and anti-IL-12/23p40 antibodies

Abstract Background All currently approved treatments for Inflammatory bowel disease (IBD) and the majority of drugs in the pipeline are anti-inflammatory agents. Clinical remission rates have reached a plateau, and there is an unmet need for agents that directly repair and regenerate the intestinal epithelial barrier as mucosal healing has been associated with improved clinical outcomes. Wnt/β-catenin signaling promotes intestinal stem cell renewal and epithelial regeneration. We have engineered a Wnt activator, SZN-1326, which increased Wnt target gene expression in the colon of mice treated with Dextran Sulfate Sodium (DSS), an animal model of IBD and demonstrated efficacy in the acute and chronic forms of this model. The goal of this study was to compare the efficacy of SZN-1326 to the anti-inflammatory agents anti-TNFα or anti-IL-12/23p40 antibodies in a chronic DSS model. Methods 7- to 8-week old female C57BL6/J mice were administered 3% DSS for three 7-day cycles separated by 7-days off, followed by a 3-day 1% DSS wash-out period. SZN-1326 was injected intraperitoneally (I.P.) at 1, 3, or 10 mg/kg for 2, 4 or 6 doses. Anti-TNFa (MP6-XT22, Biolegend) was injected I.P. at 5 or 25 mg/kg for 4 or 7 doses, and the mice were euthanized on day 38. A separate study examined the efficacy of SZN-1326 relative to anti-IL-12/23p40 (C17.8, Bioxcell) in the same model. Anti-IL12/23p40 antibody at 3 or 10 mg/kg for 4 or 8 doses was given on days 23 or 7 respectively. Results During each cycle of DSS treatment, animals exhibited a marked increase in disease activity index (DAI), characterized by body weight loss, diarrhea and bleeding. SZN-1326 at various dosing regimen (1 mg/kg for 4 doses to 10 mg/kg for 2, 4 or 6 doses) significantly improved body weights and decreased DAI compared to isotype control, while anti-TNFa or anti-IL12/23p40 had no efficacy on body weight restoration or DAI. The antibodies could be detected in the serum in accordance with their doses. Treatment with SZN-1326, but not with anti-TNFα significantly decreased colon inflammation, mucosal erosion and overall histopathological score. Further, SZN-1326 treatment significantly reduced serum levels of IL-6 and lipocalin-2, while anti-TNFa decreased only lipocalin-2 levels and anti-IL12/23p40 reduced serum IL-6 level. Conclusion In a chronic mouse IBD model, SZN-1326 at various dosing regimens stimulated intestinal epithelial regeneration, induced mucosal healing and restored the epithelial barrier resulting in reduced inflammation, improved body weight and reduced disease activity. In contrast, treatment with anti-TNFα or anti-IL-12/23p40 antibodies led to reduction only in certain serum inflammatory cytokines but had no efficacy on DAI or colon histology in this model.

Association Between Early Severe Cardiovascular Events and the Initiation of Treatment With the Anti–Interleukin 12/23p40 Antibody Ustekinumab

Ustekinumab, a monoclonal antibody targeting interleukin 12/23p40 (IL-12/23p40), is effective in the treatment of moderate to severe psoriasis, psoriatic arthritis, and Crohn disease. In 2011, a meta-analysis of randomized clinical trials reported a potential risk of severe cardiovascular events (SCEs) within the first few months after the initiation of anti-IL-12/23p40 antibodies. To assess whether the initiation of ustekinumab treatment is associated with increased risk of SCEs. This case-time-control study used data from the French national health insurance database, covering 66 million individuals, on all patients exposed to ustekinumab between April 1, 2010, and December 31, 2016, classified according to their cardiovascular risk level (high- and low-risk strata). The risk period was the 6 months before the SCE, defined as acute coronary syndrome or stroke, and the reference period was the 6 months before the risk period. Statistical analysis was performed from September 20, 2017, to July 6, 2018. The initiation of ustekinumab treatment was screened during the risk and reference periods. Odds ratios for the risk of SCE after the initiation of ustekinumab treatment were calculated. Of the 9290 patients exposed to ustekinumab (4847 men [52%]; mean [SD] age, 43 [14] years), 179 experienced SCEs (65 cases of acute coronary syndrome, 68 cases of unstable angina, and 46 cases of stroke). Among patients with a high cardiovascular risk, a statisically significant association between initiaton of ustekinumab treatment and SCE occurrence was identified (odds ratio, 4.17; 95% CI, 1.19-14.59). Conversely, no statistically significant association was found among patients with a low cardiovascular risk (odds ratio, 0.30; 95% CI, 0.03-3.13). This study suggests that the initiation of ustekinumab treatment may trigger SCEs among patients at high cardiovascular risk. In line with the current mechanistic models for atherosclerotic disease, the period after the initiation of anti-IL-12/23p40 may be associated with atherosclerotic plaque destabilization via the inhibition of helper T cell subtype 17. Although the study interpretation is limited by its observational design, these results suggest that caution may be needed in the prescription of ustekinumab to patients at high cardiovascular risk.

Anti-IL-12/23p40 antibodies for maintenance of remission in Crohn's disease.

Anti-IL-12/23p40 antibodies for maintenance of remission in Crohn's disease.

Mycobacterium tuberculosis infection in psoriatic patients treated with biologics: Real-world data from 18 Japanese facilities.

Although rare, tuberculosis has been reported with biologic treatment against psoriasis in Japan, a tuberculosis medium-burden country. Mycobacterial infection often develops after a long incubation period and might not have been adequately identified in clinical trials or post-marketing surveillance. To determine the real-world incidence of tuberculosis in psoriatic patients treated with biologics, we conducted a retrospective, multicenter, observational study in 18 facilities in Western Japan. Psoriatic patients who visited a participating facility between 2010 and March 2017 and received biologic reagents were enrolled. Information on sex, age at first biologic treatment, results of interferon-γ release assay (IGRA) for Mycobacterium tuberculosis, treatment history with isoniazid, and onset of active and/or latent tuberculosis was collected. A total of 1117 patients (830 men and 287 women) were enrolled. The mean duration of biologic treatment was 3.54years. Sixty-five patients (5.8%) showed positive IGRA results at screening. Active tuberculosis developed in two patients after the administration of tumor necrosis factor inhibitors (both involved miliary tuberculosis). Latent tuberculosis was observed in two patients treated with anti-interleukin-12/23p40 antibody. The incidence rate of tuberculosis, including latent tuberculosis, in this survey was 0.36%. Although the incidence rate of tuberculosis was low considering the observation period of biologic treatment, active tuberculosis was found in both the screening-negative group and a screening-positive subject after isoniazid prophylaxis (both miliary tuberculosis), concluding that negative screening or isoniazid treatment does not always assure that an individual has no tuberculosis. Hence, dermatologists still need to pay careful attention to tuberculosis at every patient visit.

Generation and characterization of a potent fully human monoclonal antibody against the interleukin-23 receptor

Interleukin (IL)-12 and IL-23 share a common subunit (p40) and function in T-helper (Th) 1 and Th17 immunity, respectively. Anti-IL-12/23p40 and specific anti-IL-23 antibodies are currently in clinical use for psoriasis and undergoing trials for autoimmune diseases. Since expression levels of the IL-23 receptor are likely to be much lower than those of IL-23, an anti-IL-23 receptor antibody might offer greater promise in inhibiting the IL-23-IL-17 pathways involved in inflammatory disorders. To our knowledge, no anti-IL-23 receptor antibody has been trialed in clinical studies to date. This study describes the generation and characterization of AS2762900-00, a fully human monoclonal antibody against the IL-23 receptor. AS2762900-00 bound both human and cynomolgus monkey IL-23 receptors. AS2762900-00 showed potent inhibitory effects on IL-23-induced Kit-225 cell proliferation compared to the existing anti-IL-12/23p40 antibody, ustekinumab. In a single dose administration pharmacodynamics study in cynomolgus monkeys, 1 mg/kg of AS2762900-00 significantly inhibited (> 85%) IL-23-induced STAT3 phosphorylation in blood for up to 84 days. Therefore, AS2762900-00 represents a potent novel IL-23-IL-17 pathway inhibitor with the potential to be developed into a new therapy for the treatment of autoimmune diseases.

Safety of biologics in psoriasis.

The advent of biologics brought a paradigm shift in ways to treat psoriatic patients because they have dramatic efficacy. At the same time, safety concerns about biologics have been raised. In this paper, we focus on the safety profile of biologics for psoriasis. As of 2017, six biologics are available in Japan. Two tumor necrosis factor-α inhibitors; infliximab and adalimumab, one anti-interleukin (IL)-12/23p40 antibody; ustekinumab, and IL-17 inhibitors; secukinumab, ixekizumab and brodalumab. Secukinumab and ixekizumab are anti-IL-17A antibodies. Brodalumab is an anti-IL17RA antibody. In this review, we pick up topics which have drawn attention regarding the safety of biologics and discuss them with recent published work.

Anti-IL-12/23p40 antibodies for maintenance of remission in Crohn's disease

Anti-IL-12/23p40 antibodies for maintenance of remission in Crohn's disease

Can anti-IL-12/23p40 antibodies induce remission in people with Crohn's disease?

Can anti-IL-12/23p40 antibodies induce remission in people with Crohn's disease?

Anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease.

Anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease.

Innate-like function of memory Th17 cells for enhancing endotoxin-induced acute lung inflammation through IL-22.

Lipopolysaccharide (LPS)-induced acute lung injury (ALI) is known as a mouse model of acute respiratory distress syndrome; however, the function of T-cell-derived cytokines in ALI has not yet been established. We found that LPS challenge in one lung resulted in a rapid induction of innate-type pro-inflammatory cytokines such as IL-6 and TNF-α, followed by the expression of T-cell-type cytokines, including IL-17, IL-22 and IFN-γ. We discovered that IL-23 is important for ALI, since blockage of IL-23 by gene disruption or anti-IL-12/23p40 antibody treatment reduced neutrophil infiltration and inflammatory cytokine secretion into the bronchoalveolar lavage fluid (BALF). IL-23 was mostly produced from F4/80(+)CD11c(+) alveolar macrophages, and IL-23 expression was markedly reduced by the pre-treatment of mice with antibiotics, suggesting that the development of IL-23-producing macrophages required commensal bacteria. Unexpectedly, among T-cell-derived cytokines, IL-22 rather than IL-17 or IFN-γ played a major role in LPS-induced ALI. IL-22 protein levels were higher than IL-17 in the BALF after LPS instillation, and the major source of IL-22 was memory Th17 cells. Lung memory CD4(+) T cells had a potential to produce IL-22 at higher levels than IL-17 in response to IL-1β plus IL-23 without TCR stimulation. Our study revealed an innate-like function of the lung memory Th17 cells that produce IL-22 in response to IL-23 and are involved in exaggeration of ALI.

Anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease.

Anti-IL-12/23p40 antibodies for induction of remission in Crohn's disease.

Barrier Abnormality Due to Ceramide Deficiency Leads to Psoriasiform Inflammation in a Mouse Model

It has been recognized that ceramides are decreased in the epidermis of patients with psoriasis and atopic dermatitis. Here, we generated Sptlc2 (serine palmitoyltransferase long-chain base subunit 2)-targeted mice (SPT-cKO mice), thereby knocking out serine palmitoyltransferase (SPT), the critical enzyme for ceramide biosynthesis, in keratinocytes. SPT-cKO mice showed decreased ceramide levels in the epidermis, which impaired water-holding capacity and barrier function. From 2 weeks of age, they developed skin lesions with histological aberrations including hyperkeratosis, acanthosis, loss of the granular layer, and inflammatory cell infiltrates. Epidermal Langerhans cells showed persistent activation and enhanced migration to lymph nodes. Skin lesions showed upregulation of psoriasis-associated genes, such as IL-17A, IL-17F, IL-22, S100A8, S100A9, and β-defensins. In the skin lesions and draining lymph nodes, there were increased numbers of γδ T cells that produced IL-17 (γδ-17 cells), most of which also produced IL-22, as do Th17 cells. Furthermore, IL-23-producing CD11c(+) cells were observed in the lesions. In vivo treatment of SPT-cKO mice with an anti-IL-12/23p40 antibody ameliorated the skin lesions and reduced the numbers of γδ-17 cells. Therefore, we conclude that a ceramide deficiency in the epidermis leads to psoriasis-like lesions in mice, probably mediated by IL-23-dependent IL-22-producing γδ-17 cells.

Establishment and validation of a new semi-chronic dextran sulfate sodium-induced model of colitis in mice

BackgroundThe dextran sulfate sodium (DSS)-induced model of colitis is a commonly used model of inflammatory bowel disease (IBD) in animals. However, there were few studies on the therapeutic efficacy of drugs for IBD after the onset of colitis in this model. We established a semi-chronic model of DSS-induced colitis in mice and used it to assess the therapeutic efficacy of agents for IBD. Materials and methodsColitis was induced by administration of 3% DSS in drinking water to mice for 7days followed by 5days of normal drinking water. ResultsUlcerative colitis (UC)-like symptoms including diarrhea, bloody stools and body-weight loss were observed from days 3 to 5, and continued until day 12 after DSS administration. Persistent colitis was associated with sustained local production of cytokines and was characterized by infiltration of inflammatory cells, crypt loss and erosion in the distal colon. These features are similar to those found in patients with UC. In this model, anti-tumor necrosis factor (TNF)-α antibody or anti-interleukin (IL)-12/23p40 antibody significantly ameliorated colitis when administered after the onset of colitis. However, treatment with FK506, prednisolone or sulfasalazine provided limited therapeutic benefit. ConclusionThe DSS-induced colitis established here showed similar symptomatic and histopathological features to those seen in human UC. This model may be available for predicting the clinical efficacy of candidate compounds for UC.

Opposing Roles for IL-23 and IL-12 in Maintaining Occult Cancer in an Equilibrium State

Cancer immunoediting, the process by which the immune system controls tumor growth and shapes tumor immunogenicity, consists of 3 stages: elimination, equilibrium, and escape. The molecular mechanisms that underlie the equilibrium phase, during which the immune system maintains tumor dormancy, remain incompletely defined. Here, we investigated the length of the equilibrium phase during immune control of methylcholanthrene (MCA)-induced or p53 mutant cancers and showed the critical and opposing roles of interleukin (IL)-23 and IL-12 in maintaining cancer cells in a state of immune-mediated dormancy. Inhibition of IL-23p19 was shown to reduce the malignant potential of lesions established by MCA inoculation, whereas inhibition of IL-12/23p40 enhanced tumor outgrowth. Furthermore, agonistic anti-CD40 antibody treatment mimicked the effects of anti-IL-23p19 monoclonal antibody treatment. Other cytokines such as IL-4, IL-17, TNF, and IFNαβ, which are known to play important roles either in MCA tumorigenesis or in the elimination phase of cancer immunoediting, did not play critical roles in maintaining the equilibrium phase. Taken together, our findings show opposing roles for IL-23 and IL-12 in determining the outgrowth versus dormancy of occult neoplasia and suggest a potential long-term danger in using IL-12/23p40 antibodies for treating human autoimmune inflammatory disorders.

Anti-interleukin-12/23p40 antibody attenuates chronic rejection of cardiac allografts partly via inhibition γδT cells

In our previous study, we showed that treatment with an anti-interleukin (IL)-12/23p40 antibody inhibits acute cardiac allograft rejection via inhibiting production of interferon (IFN)-γ and IL-17a. However, the impact of this antagonistic anti-p40 antibody on chronic cardiac rejection was unclear. Hearts of B6.C-H2bm12/KhEg mice were transplanted into major histocompatibility complex (MHC) class II-mismatched C57Bl/6J mice (wild-type, γδTCR (-/-) and IL-17(-/-) ), which is an established murine model of chronic allograft rejection without immunosuppression. The mice were treated with control immunoglobulin (Ig)G or 200 µg anti-p40 monoclonal antibody on post-operative days, respectively. Abdominal palpation and echocardiography were used to monitor graft survival. The mice administered with anti-p40 antibody showed a significant promotion in graft survival (median survival time >100 days), and histological analyses revealed that cardiac allograft rejection was attenuated. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence analyses demonstrated that anti-p40 antibody down-regulated the level of ingraft cytokine and chemokine expression (IL-6, IFN-γ, IL-17a, CCL2 and CCL20). Flow cytometry analyses showed that γδ T cells are an important ingraft source of IFN-γ and IL-17a and inhibit the production of inflammation cytokine by anti-p40 antibody. Compared with the wild-type group, the graft survival time in the γδ T cell receptor(-/-) and IL-17(-/-) mice was prolonged significantly. Therefore we propose that, in the chronic allograft rejection model, treatment with anti-p40 antibody prolongs graft survival possibly by reducing the amount of reactive inflammatory cells, especially γδ T cells.

Ceramide deficiency in the epidermis leads to development of psoriasis-like lesions associated with IL-23-dependent proliferation of γδ-17 cells (62.1)

Abstract It has been recognized that ceramide levels are decreased in the epidermis of patients with atopic dermatitis and psoriasis. However, the underlying mechanism by which ceramide deficiency leads to skin inflammation still remains unclear. Here, we generated Sptlc2 targeted mice under control of the keratin 5 promoter (referred to as K5-SPT-KO mice), by which their keratinocytes were devoid of serine palmitoyltransferase (SPT), the rate-limiting enzyme for de novo sphingolipid synthesis. K5-SPT-KO mice have decreased levels of ceramide in the epidermis and these mice demonstrate barrier dysfunction. From 2 weeks of age, they develop skin inflammation, showing psoriasis-like histopathologic changes and inflammatory cell infiltrates in the dermis. While expression of IFN-γ was not observed in the inflamed skin and draining lymph nodes, increased levels of IL-17 and IL-22 were detected. Strikingly, K5-SPT-KO mice showed increased numbers of γδ-T cells that produce IL-17 (γδ-17) in the skin lesion and lymph nodes and most of them also produce IL-22, similar to Th17 cells. However, much fewer γδ-17 cells are detected in the skin and lymph nodes of wild-type mice. In vivo administration of anti-IL-12/23p40 antibody ameliorated the skin lesions and reduced the number of γδ-17 cells in K5-SPT-KO mice. Therefore, we conclude that ceramide deficiency in the epidermis results in the development of psoriasis-like lesions, likely mediated by IL-23-dependent γδ-17 cells in mice.