Phospholipase A2 enzymes represent a shared pathogenic pathway in psoriasis and pityriasis rubra pilaris.

Altered epidermal differentiation along with increased keratinocyte proliferation is a characteristic feature of psoriasis and pityriasis rubra pilaris (PRP). However, despite this large degree of overlapping clinical and histologic features, the molecular signatures these skin disorders share are unknown. Using global transcriptomic profiling, we demonstrate that plaque psoriasis and PRP skin lesions have high overlap, with all differentially expressed genes in PRP relative to normal skin having complete overlap with those in psoriasis. The major common pathway shared between psoriasis and PRP involves the phospholipases PLA2G2F, PLA2G4D, and PLA2G4E, which were found to be primarily expressed in the epidermis. Gene silencing each of the 3 PLA2s led to reduction in immune responses and epidermal thickness both in vitro and in vivo in a mouse model of psoriasis, establishing their proinflammatory roles. Lipidomic analyses demonstrated that PLA2s affect mobilization of a phospholipid-eicosanoid pool, which is altered in psoriatic lesions and functions to promote immune responses in keratinocytes. Taken together, our results highlight the important role of PLA2s as regulators of epidermal barrier homeostasis and inflammation, identify PLA2s as a shared pathogenic mechanism between PRP and psoriasis, and as potential therapeutic targets for both diseases.

Regulation of inflammation by the antioxidant haem oxygenase 1.

Haem oxygenase 1 (HO-1), an inducible enzyme responsible for the breakdown of haem, is primarily considered an antioxidant, and has long been overlooked by immunologists. However, research over the past two decades in particular has demonstrated that HO-1 also exhibits numerous anti-inflammatory properties. These emerging immunomodulatory functions have made HO-1 an appealing target for treatment of diseases characterized by high levels of chronic inflammation. In this Review, we present an introduction to HO-1 for immunologists, including an overview of its roles in iron metabolism and antioxidant defence, and the factors which regulate its expression. We discuss the impact of HO-1 induction in specific immune cell populations and provide new insights into the immunomodulation that accompanies haem catabolism, including its relationship to immunometabolism. Furthermore, we highlight the therapeutic potential of HO-1 induction to treat chronic inflammatory and autoimmune diseases, and the issues faced when trying to translate such therapies to the clinic. Finally, we examine a number of alternative, safer strategies that are under investigation to harness the therapeutic potential of HO-1, including the use of phytochemicals, novel HO-1 inducers and carbon monoxide-based therapies.

The role of Dipeptidyl Peptidase-4 in cutaneous disease.

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

JAK1 rs310241 and JAK3 rs3008 Genotypes May Increase Susceptibility to Psoriasis: A Case Control Study.

BACKGROUND: Janus kinases (JAKs) are a family of non-receptor protein tyrosine kinases that are expressed in a variety of tissues. Several JAK-controlled cytokine receptor pathways are incriminated in the initiation and progression of psoriasis. Genetic polymorphisms influencing JAK expression would be anticipated to have a great impact on disease activity. OBJECTIVE: The aim of the study was to evaluate the association between JAK1 rs310241 and JAK3 rs3008 polymorphisms and the risk of developing psoriasis. METHODS: Blood samples of 150 patients and 120 controls were screened for nucleotide polymorphisms in JAK1 rs310241 and JAK3 rs3008 genes by using polymerase chain reaction (PCR)-restriction fragment length polymorphism technique. RESULTS: The GG genotype of the JAK1 rs310241 and JAK3 rs3008 genes was significantly associated with an increase in psoriasis risk (p = 0.000, OR = 7.7, 95% CI = 2.8-21.5; p = 0.003, OR = 3.3, 95% CI = 1.5-6.9, respectively). The G allele of both genes was also associated with psoriasis susceptibility (p = 0.000, OR = 2.0, 95% CI = 1.4-2.8; p = 0.002, OR = 1.7, 95% CI = 1.2-2.4, respectively). CONCLUSION: The results indicate a possible association between JAK1 rs310241 and JAK3 rs3008 gene polymorphisms and susceptibility to psoriasis. These findings validate the importance of these molecules in psoriasis and may enable the identification of the individuals most susceptible to the disease.

Matrix metalloproteinase-7 could be a predictor for acute inflammation in psoriatic patients.

PURPOSE: The pathogenesis of psoriasis is characterized by a disruption of extracellular matrix (ECM) in which matrix metalloproteinases (MMPs) participate actively. We aimed to determine MMP-7 level and its association with the inflammatory response in order to determine its usefulness as a biomarker for psoriasis prediction. We also aimed to determine its distribution in uninvolved and involved psoriatic skin to evaluate the probable role of MMP-7 in psoriasis pathogenesis. MATERIALS AND METHODS: We recruited 108 psoriatic patients and 133 healthy controls. MMP-7, tissue inhibitors of metalloproteinases (TIMPs) and interleukin-6 (IL-6) levels were measured by Enzyme-Linked Immunosorbent Assay (ELISA) assay. MMP-7 expression was detected by Immunohistochemistry (IHC) study. RESULTS: ECM turnover and inflammatory biomarker levels were significantly higher in psoriatic patients. MMP-7 revealed to be independently associated to psoriasis even after adjustment for different models. The area under the curve (AUC) of MMP-7 and inflammation Z-score were similar. MMP-7 was positively correlated with IL-6 and inflammation Z-score. Psoriasis severity (PASI) was correlated significantly with IL-6 (p = 0.007). The MMP-7 expression was detected in the epidermis of involved and uninvolved psoriatic skin. In involved skin, MMP-7 was expressed by basal and mostly suprabasal keratinocytes. In uninvolved skin, expression of MMP-7 was restricted to basal keratinocytes. CONCLUSION: MMP-7 is independently associated to psoriasis disease and to inflammatory response which make it a potential biomarker for this dermatosis.

Cimifugin ameliorates imiquimod-induced psoriasis by inhibiting oxidative stress and inflammation via NF-κB/MAPK pathway.

Cimifugin is an important component of chromones in the dry roots of Saposhikovia divaricata for treating inflammatory diseases. However, the possible effect of cimifugin in psoriasis needs further investigation. This current work was designed to evaluate the effects of cimifugin in psoriasis in vivo and in vitro, and unravel the underlying molecular mechanism. Here, we used imiquimod (IMQ) or tumor necrosis factor (TNF)-α to induce a psoriasis-like model in mice or keratinocytes. Obviously, the results showed that cimifugin reduced epidermal hyperplasia, psoriasis area severity index (PASI) scores, ear thickness and histological psoriasiform lesions in IMQ-induced mice. The decreased levels of reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT), and the accumulation of malondialdehyde (MDA) in skin tissues by IMQ were attenuated by cimifugin. Furthermore, it was observed that cimifugin effectively reversed IMQ-induced up-regulation of proinflammatory cytokines, including TNF-α, IL-6, IL-1ß, IL-17A, and IL-22. Mechanically, we noticed that cimifugin inhibited IMQ-activated phosphorylation of NF-κB (IκB and p65) and MAPK (JNK, ERK, and p38) signaling pathways. Similar alterations for oxidative stress and inflammation parameters were also detected in TNF-α-treated HaCaT cells. In addition, cimifugin-induced down-regulation of ICAM-1 were observed in TNF-α-treated cells. Altogether, our findings suggest that cimifugin protects against oxidative stress and inflammation in psoriasis-like pathogenesis by inactivating NF-κB/MAPK signaling pathway, which may develop a novel and effective drug for the therapy of psoriasis.

New JAK inhibitors for the treatment of psoriasis and psoriatic arthritis.

Psoriasis is a common inflammatory skin disease that can be associated with various pathological conditions among which arthritis is a frequent comorbidity. Based on the current pathogenetic model, development of psoriasis is mainly driven by the IL-23/IL-17A axis. Though the therapeutic armamentarium is expanding in the latest years, new therapies are needed because of the lack or loss of response or intolerance/contraindication to the currently approved drugs. The most recently developed drugs for the treatment of psoriasis and psoriatic arthritis specifically target cytokines, cytokine receptors, and intracellular signaling transducers that are involved in the pathogenesis of psoriasis. Janus kinase (JAK) pathway transduces signals of multiple cytokines, such as TNF-α, IL-23, IL-12, IFN, IL-6, IL-17, that have resulted crucial in the induction and maintenance of psoriasis inflammation. Thereby, JAK-1, JAK-3, TYK-2 belonging to the JAK family, have been identified as valid therapeutic targets in the treatment of psoriasis. Nowadays, different JAK inhibitors have been investigated in clinical trials showing promising results in terms of efficacy and safety. In this review, we systematically collected publications and data related to JAK inhibitors used in psoriasis and psoriatic arthritis providing the state-of-the-art on this new class of molecules in the treatment of these diseases.

Response to Inhibition of Receptor-Interacting Protein Kinase 1 (RIPK1) in Active Plaque Psoriasis: A Randomized Placebo-Controlled Study.

Receptor-interacting protein kinase 1 (RIPK1), a regulator of inflammation and cell death, is a potential therapeutic target in immune-mediated inflammatory diseases (IMIDs). The objective of this phase IIa multicenter, randomized, double-blind, placebo-controlled study was to evaluate safety, tolerability pharmacokinetics, pharmacodynamics, and preliminary efficacy of GSK2982772, a RIPK1 inhibitor, in plaque-type psoriasis. Psoriasis patients (N = 65) were randomized to 60 mg twice daily (b.i.d.) or three times daily (t.i.d.), or placebo for 84 days. Most adverse events (AEs) were mild with no severe drug-related AEs reported. Plaque Lesion Severity Sum improved with b.i.d. treatment compared with placebo; interpretation of t.i.d. treatment results was complicated by a high placebo response. Reductions in epidermal thickness and infiltration by CD3+ T cells in the epidermis and dermis were observed compared with placebo. Results support the rationale for additional studies on RIPK1 inhibition in IMIDs.

Activated Platelets Induce Endothelial Cell Inflammatory Response in Psoriasis via COX-1.

OBJECTIVE: Patients with psoriasis have impaired vascular health and increased cardiovascular disease (CVD). Platelets are key players in the pathogenesis of vascular dysfunction in cardiovascular disease and represent therapeutic targets in cardiovascular prevention. The object of this study was to define the platelet phenotype and effector cell properties on vascular health in psoriasis and evaluate whether aspirin modulates the platelet-induced phenotype. Approach and Results: Platelets from psoriasis patients (n=45) exhibited increased platelet activation (relative to age- and gender-matched controls, n=18), which correlated with psoriasis skin severity. Isolated platelets from psoriasis patients demonstrated a 2- to 3-fold (P<0.01) increased adhesion to human aortic endothelial cells and induced proinflammatory transcriptional changes, including upregulation of IL 8 (interleukin 8), IL1ß, and Cox (cyclooxygenase)-2 Platelet RNA sequencing revealed an interferon signature and elevated expression of COX-1, which correlated with psoriasis disease severity (r=0.83, P=0.01). In a randomized trial of patients with psoriasis, 2 weeks of 81 mg low-dose aspirin, a COX-1 inhibitor, reduced serum thromboxane (Tx) B2 and reduced brachial vein endothelial proinflammatory transcript expression >70% compared with the no-treatment group (P<0.01). Improvement in brachial vein endothelial cell inflammation significantly correlated with change in serum TxB2 (r=0.48, P=0.02). CONCLUSIONS: In patients with psoriasis, platelets are activated and induce endothelial cell inflammation. Low-dose aspirin improved endothelial cell health in psoriasis via platelet COX-1 inhibition. These data demonstrate a previously unappreciated role of platelets in psoriasis and endothelial cell inflammation and suggests that aspirin may be effective in improving vascular health in patients with psoriasis. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03228017.

Inhibition of keratinocyte necroptosis mediated by RIPK1/RIPK3/MLKL provides a protective effect against psoriatic inflammation.

Psoriasis is a common autoimmune and chronic inflammatory skin disorder globally affecting 0.51-11.43% of adults. Inflammation-associated cell death in keratinocytes plays a key role in the process of integrate inflammatory cascade in psoriasis. Necroptosis is a regulated necrotic cell death mediated by receptor interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like pseudokinase (MLKL), which participates in many human inflammatory diseases. However, the mechanism and function of programmed necrosis in psoriasis is not well-illustrated. In the current study, we provide evidence for the involvement of necroptosis in psoriasis. RIPK1 and MLKL were significantly upregulated and localized in all layers of the epidermis in human psoriatic lesions, while RIPK3 and phosphorylated MLKL were mainly expressed in keratinocytes, which located in the upper layers. Increased tendency of necroptosis was also found in IMQ-induced psoriasiform skin of mice. Further, we discovered that both the inhibitor of RIPK1 R-7-Cl-O-Necrostatin-1 (Nec-1s) and MLKL-inhibitor necrosulfonamide (NSA) suppressed necroptosis in HaCaT cells and IMQ mouse models, powerfully blocked IMQ-induced inflammatory responses in vivo, and significantly downregulated the production of inflammatory factors like IL-1ß, IL-6, IL-17A, IL-23a, CXCL1, and CCL20. These findings promote the development of new therapies for the treatment of necroptosis-activated pathologies for psoriasis.

JNK1 Signaling Downstream of the EGFR Pathway Contributes to Aldara®-Induced Skin Inflammation.

c-Jun N-terminal protein kinase 1 (JNK1) is involved in multiple biological processes but its implication in inflammatory skin diseases is still poorly defined. Herein, we studied the role of JNK1 in the context of Aldara®-induced skin inflammation. We observed that constitutive ablation of JNK1 reduced Aldara®-induced acanthosis and expression of inflammatory markers. Conditional deletion of JNK1 in myeloid cells led to reduced skin inflammation, a finding that was associated with impaired Aldara®-induced inflammasome activation in vitro. Next, we evaluated the specific role of JNK1 in epidermal cells. We observed reduced Aldara®-induced acanthosis despite similar levels of inflammatory markers. Transcriptomic and epigenomic analysis of keratinocytes revealed the potential involvement of JNK1 in the EGFR signaling pathway. Finally, we show that inhibition of the EGFR pathway reduced Aldara®-induced acanthosis. Taken together, these data indicate that JNK1 plays a dual role in the context of psoriasis by regulating the production of inflammatory cytokines by myeloid cells and the sensitivity of keratinocytes to EGFR ligands. These results suggest that JNK1 could represent a valuable therapeutic target in the context of psoriasis.

Zdhhc2 Is Essential for Plasmacytoid Dendritic Cells Mediated Inflammatory Response in Psoriasis.

Zdhhc family genes are composed of 24 members that regulate palmitoylation, a post-translational modification process for proteins. Mutations in genes that alter palmitoylation or de-palmitoylation could result in neurodegenerative diseases and inflammatory disorders. In this study, we found that Zdhhc2 was robustly induced in psoriatic skin and loss of Zdhhc2 in mice by CRISPR/Cas9 dramatically inhibited pathology of the ear skin following imiquimod treatment. As psoriasis is an inflammatory disorder, we analyzed tissue infiltrating immune cells and cytokine production. Strikingly we found that a master psoriatic cytokine interferon-α (IFN-α) in the lesioned skin of wildtype (WT) mice was 23-fold higher than that in Zdhhc2 deficient counterparts. In addition, we found that CD45+ white blood cells (WBC) infiltrating in the skin of Zdhhc2 deficient mice were also significantly reduced. Amelioration in psoriasis and dramatically reduced inflammation of Zdhhc2 deficient mice led us to analyze the cellular components that were affected by loss of Zdhhc2. We found that imiquimod induced plasmacytoid dendritic cell (pDC) accumulation in psoriatic skin, spleen, and draining lymph nodes (DLN) were drastically decreased in Zdhhc2 deficient mice, and the expression of pDC activation marker CD80 also exhibited significantly inhibited in psoriatic skin. In further experiments, we confirmed the cell intrinsic effect of Zdhhc2 on pDCs as we found that loss of zDHHC2 in human CAL-1 pDC dampened both interferon regulatory factor 7 (IRF7) phosphorylation and IFN-α production. Therefore, we identified novel function of Zdhhc2 in controlling inflammatory response in psoriasis in mice and we also confirmed that crucial role of Zdhhc2 in pDCs by regulating IRF7 activity and production of the critical cytokine. Our results finding the dependence of IFN-α production on Zdhhc2 in inflamed murine skin and in human pDCs provide rationale for targeting this new molecule in treatment of inflammation.

Inhibition of Neutrophil Elastase and Cathepsin G As a New Approach to the Treatment of Psoriasis: From Fundamental Biology to Development of New Target-Specific Drugs.

Psoriasis therapy remains an extremely relevant area of modern drug design, due to necessity of adverse reaction reduction, inherent for actual methods of therapy. It was established that two serine proteases-neutrophil elastase 1 (HNE1) and cathepsin G (CatG)-are the key agents in psoriasis development. The collected molecular data for the presented targets form the basis for the molecular modeling strategy for the search for and identification of new target-specific inhibitors. The result of this work is a group of high-priority small-molecule compounds with double-targeted affinity, which are able to suppress the pro-psoriatic processes induced by the considered serine proteases at the initial stage of the disease.

The Proteomic Profile of Keratinocytes and Lymphocytes in Psoriatic Patients.

PURPOSE: Psoriatic skin lesions are associated with chronic inflammation related to immune cell activity. Therefore, the aim of this study is to compare changes in the proteome of psoriatic keratinocytes and lymphocytes. EXPERIMENTAL DESIGN: A proteomics approach is used to analyze the expression of proteins in keratinocytes and lymphocytes from psoriatic patients and healthy controls. RESULTS: As a result 2119 proteins for keratinocytes and 1235 proteins for lymphocytes are identified. Psoriatic keratinocytes has 68 downregulated and 7 upregulated proteins and psoriatic lymphocytes has 106 downregulated and 67 upregulated proteins compared to healthy individuals. The list of downregulated proteins includes proteins involved in antioxidant homeostasis and, transcription regulation; upregulated proteins are involved in glycolytic processes and translation. These changes are accompanied by an increased level of 4-Hydroxynonenal-protein adducts; control cells are characterized by 4-Hydroxynonenal-Lysine adducts formed with structural and binding proteins, while in psoriatic cells 4-Hydroxynonenal-Lysine, 4-Hydroxynonenal-Histidine, and 4-Hydroxynonenal-Cysteine adducts with various molecular function proteins occur. CONCLUSIONS AND CLINICAL RELEVANCE: This study highlights the changes in psoriatic keratinocytes and lymphocytes that can be directly involved in the development of psoriasis. In both cell types the most significant changes are associated with upregulation of phosphoglycerate mutase 1 and downregulation of thioredoxin reductase.

Epidermal activation of the small GTPase Rac1 in psoriasis pathogenesis.

The small GTPase Ras-related C3 botulinum toxin substrate 1 (RAC1) plays a central role in skin homeostasis, including barrier function, wound healing and inflammatory responses. Psoriasis is a common skin disease characterized by deregulation of these functions, and affected skin exhibit keratinocyte hyperproliferation, inflammation and immune cell infiltration. Although psoriasis is often triggered by environmental stimulus, there is a strong genetic association with genes expressed in both immune cells and keratinocytes, of which several are linked to Rac1 signaling. Rac1 is highly active in human psoriatic lesional skin and keratinocytes, and keratinocyte-specific overexpression of an activated mutant of Rac1, Rac1V12, in a transgenic mouse model closely mimics the presentation of human psoriasis. Both Rac1 activation in keratinocytes and immune derived stimulus are required to drive psoriasiform signaling in transgenic mouse and human xenograft models of psoriasis. Therefore, understanding how increased Rac1 activation in psoriatic epidermis is regulated is central to understanding how the abnormal crosstalk between keratinocytes and immune cells is maintained.

Paraoxonases and psoriasis: negative imbalance of antioxidant endogenous mechanisms.

BACKGROUND: Numerous reports have shown that psoriasis patients are more exposed to lipoprotein peroxidation and to a decrease in the activity of paraoxonase (PON)1, an antioxidant and anti-inflammatory enzyme. Thus, it has been suggested that malfunction of the antioxidant system and an increased production of reactive oxygen species drive immune inflammatory events, that result in progressive skin cell damage in patients with psoriasis. The PON protein family, including PON1, PON2 and PON3, is one of the most important endogenous defense mechanisms against oxidative stress. In the present study, we investigated PON gene expression in psoriasis and in cutaneous oxidative stress. METHODS: The study population included 10 patients affected by moderate-to-severe plaque psoriasis and 15 healthy donors who have undergone to plastic surgery, were used as control. Skin punch biopsies of lesional and non lesional psoriatic skin were performed for analysis of PON2 and PON3 gene expression. In addition, oxidation assays in ex vivo full-thickness healthy skin organ cultures were performed. RESULTS: No significant differences were observed between PON2 and PON3 gene expression in psoriatic lesional and non lesional skin compared with healthy controls. H2O2 treatment induced a significant decrease of PON2 and PON3 expression in ex vivo full-thickness healthy skin organ cultures; conversely the pretreatment of samples with the antioxidant reagent N-acetyl-L-cysteine (NAC) induced a significant increase. Interestingly, no significant alterations were reported for PON2 and PON3 expression in ex vivo full-thickness healthy skin organ cultures stimulated with IL-17. CONCLUSIONS: Taken together our findings have revealed that a strong pro-oxidative activity is not effectively countered by antioxidant endogenous mechanisms both in psoriatic skin and in ex vivo experimental model.

Antipruritic Effects of Janus Kinase Inhibitor Tofacitinib in a Mouse Model of Psoriasis.

The Janus kinase 1/3 inhibitor tofacitinib has demonstrated an antipruritic effect in two phase III studies in psoriasis. However, the mechanisms behind this antipruritic effect are still unknown. We presently investigated whether tofacitinib affects spontaneous itch as well as expression of itch-related cytokines and epidermal nerve fiber density (ENFD) in the imiquimod-induced mouse model of psoriasis. Psoriasis-like skin lesions were produced by daily topical application of imiquimod to the back skin. Imiquimod treatment resulted in spontaneous scratching, which was significantly inhibited by tofacitinib treatment. Imiquimod treatment significantly increased mRNA expression of Il22, Il23, and Il31, reduced peptidergic ENFD, and increased nonpeptidergic ENFD compared to naive mice. Tofacitinib significantly decreased the expression of those cytokines and increased peptidergic ENFD without a significant effect on nonpeptidergic ENFD. Tofacitinib may inhibit psoriatic itch through inhibition of cytokine expression as well as modulation of epidermal innervation.

Lack of Effect of 12-Week Treatment with Risankizumab on the Pharmacokinetics of Cytochrome P450 Probe Substrates in Patients with Moderate to Severe Chronic Plaque Psoriasis.

OBJECTIVE: The objective of this study was to characterize the effects of risankizumab on the in vivo activity of cytochrome P450 (CYP) 1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A in psoriasis patients using a cocktail approach. METHODS: Patients with moderate to severe chronic plaque psoriasis (n = 21) received single oral doses of sensitive probe substrates for CYP1A2 (caffeine 100 mg), CYP2C9 (warfarin 10 mg), CYP2C19 (omeprazole 20 mg), CYP2D6 (metoprolol 50 mg), and CYP3A (midazolam 2 mg) on day 1, followed by 12 weeks of subcutaneous risankizumab treatment of 150 mg once every 4 weeks from day 8 to day 92, and again the same cocktail of substrates on day 98. Serial blood samples were collected for determination of the CYP probe drugs and metabolites with and without risankizumab. Trough samples were collected for risankizumab. RESULTS: The 90% confidence intervals (CIs) for the area under the plasma concentration-time curve (AUC) from time zero to infinity (AUC∞) ratios for the CYP probe substrates administered with risankizumab versus without risankizumab were within the default 0.8-1.25 equivalence bounds. Similar results were observed for maximum plasma concentration (Cmax), except for omeprazole, for which the lower bound of the 90% CI for Cmax (0.73) extended slightly below the default equivalence limit. No differences were observed in metabolite-to-parent drug Cmax or AUC ratios with risankizumab versus without risankizumab. Risankizumab trough plasma concentrations significantly exceeded those of the phase III regimen of risankizumab in psoriasis (150 mg subcutaneously at weeks 0 and 4 and every 12 weeks thereafter). CONCLUSIONS: Risankizumab did not affect the in vivo activity of CYP1A2, CYP2C9, CYP2C19, CYP2D6, or CYP3A enzymes in patients with moderate or severe plaque psoriasis and therefore has no potential for drug interactions through these enzymes. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02772601.

Inhibition of spleen tyrosine kinase attenuates psoriasis-like inflammation in mice through blockade of dendritic cell-Th17 inflammation axis.

Psoriasis is a debilitating autoimmune disease of the skin characterized by acanthosis and hyperkeratosis resulting from excessive growth of keratinocytes in the epidermis and inflammatory infiltrates in the dermis. Innate immune cells such as dendritic cells (DCs), perform a critical role in the pathophysiology of psoriasis by presenting inflammatory/costimulatory signals for differentiation of Th17 cells. Recent studies point to the involvement of spleen tyrosine kinase (SYK) in inflammatory signaling cascade of DCs. However, it is yet to be determined whether SYK inhibition in DCs would lead to diminishment of psoriatic inflammation. Therefore, our study evaluated the effects of SYK inhibitor, R406 on imiquimod (IMQ)-induced psoriasis-like inflammation, expression of costimulatory/inflammatory molecules in DCs and their relationship with Th17/Treg cells. Our data show that R406 causes attenuation of IMQ-induced dermal inflammation as shown by reduction in ear/back skin thickness, acanthosis and myeloperoxidase activity. This was concurrent with reduction in inflammatory cytokines and co-stimulatory molecules in CD11c + DCs such as IL-6, IL-23, MHCII, and CD40. This favoured the suppression of Th17 cells and upregulation of Treg cells in R406-treated mice with psoriasis-like inflammation. Direct activation of TLR7 by IMQ in splenocytic cultures led to increased SYK expression in CD11c + DCs and release of IL-23/IL-6. IMQ-induced IL-6/IL-23 levels were significantly diminished by SYK inhibitor, R406 in splenocytic cultures. In essence, our study shows that SYK inhibition supresses psoriasis-like inflammation by modifying DC function in mice. Further, it implies that SYK inhibition could be a prospective therapeutic approach for the treatment of psoriasis-like inflammation.