Project description:Psoriasis is a chronic inflammatory skin disorder underpinned by dysregulated cytokine signaling. Drugs neutralizing the common p40 subunit of IL-12 and IL-23 represented a therapeutic breakthrough; however, new drugs that block the IL-23p19 subunit and spare IL-12 are more effective, suggesting a regulatory function of IL-12. In order to pinpoint the cell type and underlying mechanism of IL-12 mediated immune-regulation in psoriasis we generated a conditional Il12rb2-knockout (KO)/reporter mouse strain. We detected Il12rb2 expression in T cells and a specific subset of interfollicular (IF) keratinocytes. Analysis of scRNAseq data from psoriasis patients confirmed this expression pattern in the human skin. Mechanistically, deletion of Il12rb2 in the keratinocyte compartment led to exacerbated psoriasiform inflammation. Protective IL-12 signaling blocked the hyperproliferation of keratinocytes, maintained skin barrier integrity, and, importantly, diminished disease-driving IL-23/type 3 immune circuits. Collectively, we provide a potential explanation for the superior efficacy of IL-23p19 inhibitors in psoriasis and describe an unperceived role of IL-12 in maintaining skin epithelial cell homeostasis.
Project description:miR-146a acts as a negative feedback regulator of inflammation. To investigate the role of miR-146a in psoriasis psoriasiform skin inflammation was indeuced in Mir-146a-/- and wild type mice (C57BL6J) by topical applciation of imiquimod (IMQ)-cream (Aldara). Gene expression profiling (Affymetrix) was used to identify transcriptomic changes associated with psoriasis-like skin inflammation in wild type vs. miR-146a -/-mice. A daily topical dose of 31.25 mg of Aldara cream (5% IMQ) was applied on the right ear of miR-146a -/- and C57BL/6 mice on three consecutive days to induce psorisis-like skin inflammation. Mice were sacrificed at day 4. Ear flaps were collected for total RNA extraction and hybridization on Affymatrix GeneTitan plate format Gene ST 2.1 (mouse).
Project description:miR-146a acts as a negative feedback regulator of inflammation. To investigate the role of miR-146a in psoriasis psoriasiform skin inflammation was indeuced in Mir-146a-/- and wild type mice (C57BL6J) by topical applciation of imiquimod (IMQ)-cream (Aldara). Gene expression profiling (Affymetrix) was used to identify transcriptomic changes associated with psoriasis-like skin inflammation in wild type vs. miR-146a -/-mice.
Project description:IL-6 inhibition has been unsuccessful in treating psoriasis, despite high levels of tissue and serum IL-6 in patients. Additionally, de novo psoriasis onset has been reported following IL-6 blockade in rheumatoid arthritis patients. To explore mechanisms underlying these clinical observations, we backcrossed an established psoriasiform mouse model (IL-17C+ mice) with IL-6 deficient mice (IL-17C+KO) and examined the cutaneous phenotype. IL-17C+KO mice initially exhibited decreased skin inflammation, however this decrease was transient and reversed rapidly, concomitant with increases in skin Tnf, Il36α/β/γ, Il24, epigen and S100a8/a9 to levels higher than those found in IL-17C+ mice. Comparison of IL-17C+ and IL-17C+KO mouse skin transcriptomes with that of human psoriasis skin, revealed significant correlation among transcripts of psoriasis patient skin and IL-17C+KO mouse skin, and confirmed an exacerbation of the inflammatory signature in IL-17C+KO mice that aligns closely with human psoriasis. Transcriptional analyses of IL-17C+ and IL-17C+KO primary keratinocytes confirmed increased expression of proinflammatory molecules, suggesting that in the absence of IL-6, keratinocytes increase production of numerous additional proinflammatory cytokines. These preclinical findings may provide insight into why arthritis patients being treated with IL-6 inhibitors develop new onset psoriasis and why IL-6 blockade for the treatment of psoriasis has not been clinically effective.
Project description:IL-6 inhibition has been unsuccessful in treating psoriasis, despite high levels of tissue and serum IL-6 in patients. Additionally, de novo psoriasis onset has been reported following IL-6 blockade in rheumatoid arthritis patients. To explore mechanisms underlying these clinical observations, we backcrossed an established psoriasiform mouse model (IL-17C+ mice) with IL-6 deficient mice (IL-17C+KO) and examined the cutaneous phenotype. IL-17C+KO mice initially exhibited decreased skin inflammation, however this decrease was transient and reversed rapidly, concomitant with increases in skin Tnf, Il36α/β/γ, Il24, epigen and S100a8/a9 to levels higher than those found in IL-17C+ mice. Comparison of IL-17C+ and IL-17C+KO mouse skin transcriptomes with that of human psoriasis skin, revealed significant correlation among transcripts of psoriasis patient skin and IL-17C+KO mouse skin, and confirmed an exacerbation of the inflammatory signature in IL-17C+KO mice that aligns closely with human psoriasis. Transcriptional analyses of IL-17C+ and IL-17C+KO primary keratinocytes confirmed increased expression of proinflammatory molecules, suggesting that in the absence of IL-6, keratinocytes increase production of numerous additional proinflammatory cytokines. These preclinical findings may provide insight into why arthritis patients being treated with IL-6 inhibitors develop new onset psoriasis and why IL-6 blockade for the treatment of psoriasis has not been clinically effective.
Project description:The DEAD-box (DDX) proteins function in diverse cellular processes including RNA alternative splicing, and are linked to immune-mediated diseases. However, little is known about the roles of DDXs in skin inflammatory diseases. Here, we show that DDX5, one of the founding members of the DDX RNA helicase family, controls skin inflammation and participates in the pathogenesis of psoriasis via regulating IL-36R pre-mRNA splicing. We found that both mRNA and protein of DDX5 are decreased in lesional skin from patients with psoriasis and psoriasis-like mice, and that mice with keratinocyte-specific ablation of DDX5 spontaneously develop psoriasis-like phenotypes. Mechanistically, DDX5 complexes with serine/arginine-rich splicing factor 1(SRSF1) to typically regulate IL-36R pre-mRNA splicing in keratinocytes, which generates mRNAs encoding full-length IL-36R and a previously unknown soluble form of IL-36R (sIL-36R). sIL-36R controls IL-36/IL-36R signaling by competing with IL-36R for IL-36γ ligation. The reduction or deficiency of DDX5 leads to IL-36R pre-mRNA splicing preferring to the generation of IL-36R but not sIL-36R, thereby selectively amplifying inflammatory responses of keratinocytes to IL-36γ and then aggravating cutaneous inflammation in psoriasis. Genetic restoration or intradermal administration of sIL-36R in psoriasis-like mice suppresses IL-36R signaling and alleviates the disease phenotype of psoriasis. Altogether, these data reveal a pathogenic role of DDX5 during psoriasis, and provide mechanistic insights into the regulation of IL-36R splicing and its impact on psoriasis development.
Project description:Atopic dermatitis (AD) is a debilitating inflammatory skin disorder. Biologics targeting the IL-4/IL-13 axis are effective in AD, but there is still a large proportion of patients that do not respond to IL-4R blockade. Further exploration of potentially pathogenic T cell-derived cytokines in AD may lead to new effective treatments. This study aimed to investigate the downstream effects of IL-26 on skin in the context of type 2 skin inflammation. We found that IL-26 alone exhibited limited inflammatory activity in skin. However, in presence of IL-1β, IL-26 potentiated the secretion of TSLP, CXCL1 and CCL20 from human epidermis through JAK/STAT signaling. Moreover, in an in vivo AD-like skin inflammation model, IL-26 exacerbated skin pathology and locally increased type 2 cytokines, most notably of Il13 in skin T helper cells. Neutralization of IL-1β abrogated IL-26-mediated effects, indicating that the presence of IL-1β is required for full IL-26 downstream action in vivo. These findings suggest that the presence of IL-1β enables IL-26 to be a key amplifier of inflammation in the skin. As such, IL-26 may contribute to the development and pathogenesis of inflammatory skin disorders such as AD.